I think if a sponsor says they ALWAYS convert at 1:200 they are probably not being truthful. But if they're saying their overall average is 1:100 or 1:200, I can believe that.

For example, we have a lot of affiliates that convert at better than 1:100 consistently, but at the opposite end, we have some affiliates sending junk traffic that converts at 1:5000, and a couple that convert 1:1000. But our overall is still less than 1:200... and of course, as you know, it all depends on what sort of traffic a given sponsor is getting from his affiliates. If somebody sends us college boy traffic it probably won't convert very well. If they send us bear traffic, I'd be shocked if it converted at anything better than 1:5000. But if they send us twink traffic, it's not at all uncommon to see 1:60 or 1:75 even after several months.

Of course, like anything else, I suspect that some sponsors lie just to get more affiliates... but that's rather short sighted because once affiliates realize that a site doesn't convert, they drop it and rarely try it again.