Was easy money around 2002-2004. You'd get like 200:1 conversion of an OK paysite with either a 35% lifetime revshare of sometimes random promotions (usually to kickstart a new site) would offer $250 upfront PPS. Niche sites (gay, extreme fetish) would convert TGP traffic as good as 75:1 and honestly were the best place to be (to many fanboy affiliates saturating the market with mainstream "teen amateur" sites).
2005-2008, TGP's totally died to Tubes. And Tubes generally killed the value in hosted galleries (a key marketing tool for affiliates alongside TGPs). Last I heard of old contacts, they'd either tried to move up the food chain intro production (which mostly moved to eastern europe), moved into niche tube sites, or sold up (as I did) and went into mainstream web. Actually, probably the most money I made was from sale of site network and domain portfolio.