diff --git a/README.md b/README.md
index e7e2522..1c1ab2b 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,10 @@ http://crisp.bringyour.com:7154                      # plain HTTP
   URL directly.
 - Proxies are residential but shared: several accounts can land on the same provider
   (two `Vodafone Hildesheim` exits were seen), so `unique_ip` is the metric, not `alive`.
+- **Not every exit is residential.** A proxy created with `country_code: br` came back as
+  `209.50.178.206 AS200373 3xK Tech GmbH, Toronto` — a hosting ASN in the wrong country. The network
+  is P2P, so peers supply the exit; check `ipinfo` (`org`/`country`) per proxy before trusting it for
+  anything geo-sensitive, and drop rows where the ASN is a hosting provider.
 
 ## Scope