eBays Prohibited and Restricted Items: Overview conditions are broken everyday.Look at the items listed under questionable, and your are virtually guaranteed to see most of those or very similar items listed on a daily basis.
So what are these 'Dell' machines Dell selling off overstock[ does happen I've seen Dell items on a reputable surplus stock dealer] or an Oriental Rip Off Merchant? If it is the the latter Dell must by now be aware and sanctioning E-Bay in some way.
I had a look myself and as you say it appears the feedback are from fictitious bidders which is why I presume they were removed, but why has the guy still got positive feedback, even supposing they can't prove the guy was involved the least they could do would be remove all the suspect positive feedback from the bidders they kicked off don't you think. Perhaps they've been kicked off for something else.