I would recommend checking out the sites that are in any affiliate program, before you join! A simple google search of the sites will reveal if the affiliate is representing bad sites. Just that simple step will tell you volumes about the honesty of the program you are thinking of joining.
Yes - you should have read the T&Cs, however, isn't it our responsibility to help decipher them for our visitors - for example, saying things like , you specifically have to do X, Y and Z to get your free bonus, then you should consider quitting (that's my usual advice!).
I also only make referrals and recommendations to sites I have signed up with and used personally, and I ask everyone else who writes for us to do the same - that way you can explain the login/registration process a little too (gives you more to say for one thing - unique content etc!).