By the same standards as googling discussed below. Where does netiquette come into linking?
If you intend to blog a link to a site should you ask before you link? Of course most bloggers go through their referrals files like gold dust and will not only find but click back on anything that looks out of place so they will find your link. So should you ask permission to link? Personally I think that’s a silly option, but at the same time it can feel strange sometimes to link to a complete stranger because of something of interesting on their site. Yah I know not really going anywhere with this and not really in a realistic place with this either.
soundtrack: “Rag Doll” by Aerosmith