Eventually these things get fixed with zone revamps, etc. Also, once the price drops enough, nobody is going to WANT to farm the item. I was in mielb last night and killed the Offerer camp and after I broke the camp I decided to leave. Because selling a cloak for 1k isn't worth my time of sitting there. Especially knowing how long I've sat there before and NEVER had a cloak drop.
It's plenty rare. It's just that some people have a lot of free time to sit around.