Most Helpful Guy
I never have and never will. Why?
Because I think of it like this:
The only reason why someone would do that is because they hate their ex and don't want them to be happy with someone. Or maybe your just jealous. Well... if you ex was that bad of a person, then if you let them be with someone new (know that it wouldn't work because they are a terrible person), their hurt and pain will only be worst if the new couple is toether for a longer time - more time = more pain.
So I told someone to beware of my ex, I would only be doing them AND my ex a FAVOR. Why would you want to do you ex a favor? Let them suffer!