Sins are actions that you must not do.
This article lists actions I find unworthy, gross, miserable or otherwise bad. My opinion is not a religion, so this list cannot be called a list of sins in the literal sense, but the whole vibe might be similar!
I try to avoid doing these things. I want others people to do the same. The list is always work in progress.
There are exceptions for every sin. I'm not ready or willing to list them all.
Well, for impersonation, there is a trivial exception: entertainment. It is alright to pretend to be someone else in a play or in a film. That's what they are about, after all. Think about the rest in a similar fashion.
Alex has some observations on torture.