I know this is terrible, but I don't let my nephews play with my boys toys. They are 2 and 4 so they don't need to be playing with infant toys anyway.
I just tell them that they are big boys and play with big toys not baby toys. It works for the 4 year old, but I have a tough time keeping the 2 year olds grubby hands off. LOL! I take a wet washcloth with dishsoap on it to clean my boys cloth toys that can't go in the washing machine. I hate those kind of toys but he loves them.