Do you know, I have cleaned a few "The Rug Doc Waz ere" carpets in the past, But i never found any foam problems when extracting. I mean there's chems are total pants, but doesn't seem to be high foam.
I guess you can leave carpets with a high PH and loads of stick residue but without the foam build up.
Spotters like vanish, 1001 etc thats a different story! Had a right nasty one this week that caught me by suprise! Baaastard!
Tony