If the illegal search is like a burglary. But if I happen to poke through the trunk of someone's car I doubt if I'd go to jail for it or anything. On the other hand, if I do have probable cause to believe that some illegal activity is going on inside a house, and there isn't time to call the police, a jury would most likely consider my actions reasonable under the circumstances if I were to enter.
All illegal searches are burglaries if performed by private citizens, because we never have the the right to perform a legal search - and whether you went to jail would depend on what you took, prior record, etc. I don't think I'd like to see cops prosecuted by that standard, because it really isn't the same crime. I was thinking of something more along the lines of suspension without pay, busted in rank, etc., depending on the severity. Right now, in general, there is no penalty at all.
Anyway, good chatting with you. It sounds like we mostly agree - the devil is in the details, as always...