Buy a batch of static IPs, run your usual pre-flight checks, and watch three reputation databases hand back three unrelated answers. A poster on r/proxies described exactly this recently: one IP, three checkers, three verdicts. IPQS scored it a 4, effectively clean. Scamalytics put the same address at 78, deep in fraud territory. IP2Location flagged it as proxy detected. His conclusion was mostly sarcasm. Fair enough.
The disagreement is not a glitch. We operate thousands of static ISP addresses at BirdProxies and probe their reputation continuously, and checkers contradicting each other is the normal state of the world, not an edge case you stumbled into. Here is what each score actually measures, why the aggregate number is not what blocks you, and the one test that predicts anything.
Why reputation databases disagree about the same IP
Reputation databases disagree because each one measures a different thing: IPQS mixes fraud reports with behavioral signals, Scamalytics weighs the network operator and shared subnet history, and IP2Location mostly classifies what kind of range the address is registered in. They are not three thermometers reading one temperature. They are a thermometer, a barometer, and a land registry, and people keep comparing their outputs as if the units matched.
None of them observes the thing you care about, which is how the target site reacts when your traffic arrives. Every public checker works from its own partial evidence: abuse feeds it subscribes to, honeypots it runs, registration paperwork it parses, customer reports it aggregates. Different evidence, different verdict. Same IP.
What each checker is actually measuring
Each of the three checkers in that Reddit thread answers a different question, and knowing the question explains the score.
IPQS: fraud reports and behavior
IPQS leans on reported fraud and behavioral signals tied to an address, so a low score usually means nobody has recently done anything loud from that specific IP. That is genuinely useful information. It is also narrow. A freshly rotated IP with no history scores well by default, and an address whose neighbors are all burned can still show a 4 because the evidence IPQS weighs is per-address.
Scamalytics: the operator and the neighborhood
Scamalytics scores the hosting operator and the shared history of the surrounding range heavily, so one abusive neighbor on your /24 can push your number into the red while your own address never sent a bad packet. A 78 there often reads less as "this IP did something" and more as "this block, or this company, has a record." Guilt by postal code. If you bought a static IP from a provider whose other ranges saw abuse, this checker is the one most likely to hate you for it.
IP2Location and other range classifiers: paperwork, not behavior
IP2Location and similar databases mostly label the type of range, so a perfectly clean address inside a hosting-registered block will show proxy detected forever, no matter how it behaves. This is classification, not judgment. The label changes when the registration data changes, which can take months, or never. An ISP-registered address on a datacenter company's ASN will confuse these databases indefinitely, and no amount of good behavior fixes a paperwork verdict.
The verdict that blocks you is not on any of these sites
The score that actually gets you blocked is the private one computed by the site you are visiting, and no public checker can see it. Google runs its own detection. So do Meta, every sneaker shop, every bank, every streaming service. Each of them combines its own abuse logs, session history, device fingerprints, and traffic patterns into a decision that never leaves the building.
This cuts both ways. An address that looks radioactive on Scamalytics can work flawlessly on the one site you care about, because that site has never seen anything bad from it. A squeaky-clean address can eat an instant captcha wall on another site that got burned by its previous tenant. The public score and the private decision are only loosely correlated.
A second thread, this one from a traveler on r/VPN, shows the same mechanics from the consumer side: more proxy detection, inconsistent streaming, occasional login flags, all on a connection that any single checker might call fine. Shared exit IPs carry the accumulated history of everyone who used them, and each service reacts to its own slice of that history. The experience feels unpredictable precisely because there is no single ledger.
One database verdict is a rumor. The target's behavior is the fact.
A pre-flight check that actually predicts something
A pre-flight check worth running has three steps: confirm the ASN type matches what you bought, cross-check the geolocation in more than one database, then test the exact target with a throwaway session before anything real touches the IP.
1. Confirm the ASN type
Look up the ASN and check that its registration matches the product. If you paid for residential or ISP addresses and the range sits on a well-known hosting ASN, stop there. Range classifiers will mark it as datacenter traffic for the life of the address, and many targets treat that label as reason enough to challenge you.
2. Cross-check the geolocation
Check the claimed location in at least two databases, because geolocation data lags reality by weeks or months. IPs get moved between networks and regions, and databases update on their own schedules. A third Reddit thread, about an IP showing the wrong location even with the VPN off, is this lag in the wild: the connection changed, the databases had not caught up. Wrong or stale geo breaks region-locked content and trips risk checks that compare your IP location against your account history.
3. Test the real target
Run a throwaway session against the actual site you plan to use. Log in with a burner account, load pages the way you normally would, and watch for captchas, silent feature limits, or verification prompts. Ten minutes of this tells you more than every reputation dashboard combined, because it is the only test that consults the ledger that counts. If you want a fast first pass before that, there is a free IP fraud score checker at birdproxies.com/tools/ip-fraud-score and a proxy tester at birdproxies.com/tools/proxy-tester. Treat them like any checker: a filter, not a verdict.
Reputation sticks to the subnet, not just the IP
Abuse reputation attaches to whole ranges, typically the /24, so one bad actor can taint a couple hundred addresses that did nothing. Blocklists ban ranges because abusers rotate within them. Scoring systems inherit that logic. This is very likely what produced the 78 in the opening story: not that address, its street.
The practical consequence for providers is that IP hygiene has to be managed per subnet, not per address. Ranges need to be probed against real targets before they are handed to customers, dirty subnets need to be retired rather than resold, and an address that goes bad in use needs to be swappable. We test our subnets against the specific retail targets our customers care about before allocating from them, and we swap addresses that went sour. Ask any provider you evaluate how they handle exactly this. The answer is revealing.
What no provider can honestly promise
No provider can promise a universally clean IP, because clean is relative to the target and every target keeps its own books. An address can be spotless for Google and burned for one sneaker shop that tangled with its previous owner. Nobody selling IPs controls the private blocklists of every site on the internet, and anyone promising a zero fraud score on every public checker is selling you the weather.
What a provider can honestly offer is narrower and more useful: correctly registered ASNs, geolocation that matches the label on the box, subnets probed against real-world targets, and a swap path for addresses that go bad. What you can do is just as narrow. Judge an IP by how your target treats it. Everything else is commentary.