Yes there's a lot of crap, but there are also a lot of great products, eg www.rocketspanish.com, www.jamorama.com, www.000relationships.com, www.rocketgerman.com, www.singorama.com, just to name a few. And quite a few people are making thousands a day on clickbank, I know a few anyway.
From a merchant's standpoint, we avoided clickbank as a card processor for several reasons. First and foremost they immediately want to integrate your private sector earnings with the IRS - requiring you to obtain an EIN even though we don't employ anyone. Also, a max earning cap is placed on affiliates without an EIN - which is absurd. Another concern (for affiliates too) is clickbank's security threshold - it's set way too high for card processing - and causes a lot of missed sales. We've personally seen cases where the customer's card was refused, only to have it accepted 10 minutes later elsewhere by a competitor.
Ya CB does have some weird stuff going on like that, but as an AFFILIATE clickbank definitely has a lot of income potential.