its a bit like tigernuts mick, one or two start using small bags of them with no freebies and do well. others start using them and catch a few. someone then puts in 5kg, and has a result - therefore 10kg will be better! before you know it, everyones spodding sacks of the stuff in and the fish suffer.
to be honest, i dont think the selling thing will be as much of a problem with groats, as they are small to begin with, the carp shouldnt have too much trouble passing them...but why risk it? and surely they are more attractive with the oils etc coming out? if you fished them dry just to get them in a bag, like i've said imho there's better ways of doing it.