Clickbank does not shave. They may have some eventual tracking problems like any other network. I have seen sales credited 4 o 5 days after the purchase was done. CB could have kept this money , if they pretend to shave but they always inserted the commission in the account.
Some vendors have "tricky manners " like forcing the visitor to op-int their email before going to the order form or placing a " contact number " or "phone us here" on the top of the site. Indeed what they are focusing is retaining the info of the visitor because not everyone buys at first, rather than shaving the affiliate commission. Simply stay away from this kind of products.
Analyze the copy sale before you start promoting a product. Watch the entire video or read the full page.