Please explain why it is a problem for you.
I haven't been able to test the feature yet, but I can offer some places where it might be unwelcome for me.
I have a significant number of albums that were recorded by local bands, they never broke out and got famous, but they put out a few CDs. There is no "correct" cover art available for many of those albums online, and I've been too lazy to scan the CD sleeves, so I've left the art blank on the albums. In the past when I tried to look up cover art for those albums, the internet does find cover art, but it finds the wrong cover art! Either another band had a similarly named album, or someone has posted the cover art for the wrong album by that artist under the wrong album name. So a search to, say, google or freedb, will return cover art, but it's wrong. In those cases I'd rather have no cover art than wrong cover art, so I'd also like a way to deal with that case.
There are a few different solutions:
1) One way to deal with it would be an option to disable like folks are asking for above;
2) Another, maybe more useful, way to address it would be to prompt users and allow them to accept or reject the art (maybe with a check box "don't ask me again for these files")
3) A workaround for folks in the meanwhile is to make "dummy" empty cover art and put it in your empty files. That would stop the lookup. With a smartlist that would take ten minutes.