I have been on both sides of the warning issue...giving and receiving.

When giving a warning, I always preface it with..."This has been my experience with such and such individual." I also include specific situations that happened to back up my opinion. I do this rarely, and only when I can see that a real issue could evolve.

As far as being on the receiving end of warnings, I always ask the warner to give me specifics..tell me what happened to make them feel that they need to warn me.

Granted, there are times when folks are trying to make your decisions for you regarding who you associate with. Everyone has a specific agenda. All we can do is sort through the muck and decide for ourselves who to associate with and who not to. And I for one try not to judge those who warn.....I just try to understand why.