For a while, I have thought about this. I believe links with swears and/or other slightly innaproppiate content should be allowed outside PM, as long as the user who is linking accompanies it with a warning (Example: WARNING CONTAINS SWEARS). To me, it is no different from linking it in PM. If someone is offended by swears or the latter, they will know whether to click on the link or not. In the past, I have seen admins do it, and it wasn't a problem. Also, I have come across at least one wiki which allows it.
To avoid someone abusing that privilege, we should put in some limits. Example: Porn is a definite no.
Any ideas?