Every request a site receives is scored partly on the address it came from. The main inputs:
- Network type. The ASN shows whether the address belongs to a consumer ISP, a mobile carrier or a hosting company. Hosting space starts with less trust.
- Blocklists. Spam, abuse and open proxy lists such as Spamhaus's are consulted widely.
- History. Anti-bot vendors see traffic across thousands of sites. An address that scraped aggressively yesterday elsewhere can arrive with a poor score today.
- Neighbours. Reputation spreads across a subnet, so a clean IP in a dirty /24 can suffer for it.
Why proxy buyers care
Reputation is the part of a proxy you cannot see on a pricing page and cannot fix with code. It explains why a shared proxy can be blocked before you send a request, and why dedicated IPs and less-abused networks cost more.
How to check an IP
Look the exit up on a public checker such as AbuseIPDB or Spamhaus's IP lookup, and check its network type:
curl -s -x http://USERNAME:PASSWORD@HOST:PORT https://ipinfo.io/json
A clean blocklist result is necessary, not sufficient: commercial anti-bot scores are private. The honest test is your real target. Run a sample of requests and count blocks and challenge pages, the method in how to test a proxy provider.
Common confusion
Reputation is not permanent in either direction. Scores decay as an address behaves, and they drop again if you or a co-tenant send too fast. Pacing your own traffic, covered in how to avoid getting blocked, protects the reputation of the IPs you pay for.