IMO, all kidding aside (and I think my ears are still intact

) it depends very much on the player.
Championship level stiffs are probably fair game for loans. Championship level youth team players are probably OK for perm transfers (Barnet have their midfield anchored by a former Norwich trainee who they signed last summer).
EPL players - I'd say youths only are likely to do low level loans - older reserves are unlikely to drop that far unless they are out of contract and toward the end of their career.
But as has been said, it's a personal preference and there is no consensus. I tend to only loan players in emergencies anyway