I don't find run selling appealing - it is kind of like paying gil to someone else to play the game for you - and I am not a fan of run selling shouts or listing in PF, but I think it is within the terms of service of the game and overall it doesn't affect me much. Some people must find it valuable.

I guess it could result in some people seeming to be more experienced or skilled at certain fights than they actually are, but that could happen regardless of whether they paid for the carry or not. I suppose that gil buying players might also buy clears, but there is lots of expensive stuff on the market board anyway that they could spend their ill gotten gil on anyway.