Man, you should see the list of stuff that people try to drop off.....A lot of the time, they sneak stuff in and just dump it in a tank.
Most of your 'common' pet shop sharks are things we just laugh at. Black tips, nurse, some wobbs and the like. Most places won't even take bamboo or cat sharks anymore. From our stand point, all we're doing is aiding the bad habits of pet owners who have no clue. Not to mention who knows what types of issues we'd be introducing into our large collections (even after quarantine). The thing is a lot of people see a type of animal at a facility, and they assume that if they buy one, that facility will take it. Usually, we don't. We have our own channels to aquire animals through. It's a detail we look at when opening an exhibit. It's also the biggest reason I don't want to display pacu and oscars. But since we are going to have pacu, I'm going to make a few signs talking about why the public should NOT buy them.
As an example, there was a guy who tried to donate his nurse about a month ago. It was almost three feet....way too big for his home tank, but at three feet would be a snack to the other sharks we house our nurse population with.