I do think that the search filters and subcategories could possibly be refined a little more to help with this, at least if your search is more specific you can filter out what you don't want to see a bit more easily.
I have not seen the ability to hide sellers on any site,although on Ebay's user forums you can hide all content from another member so I suppose it is possible to do it ...but would it be in Ebid's interest to do so?