I dont think it is rude at all, i always take my shoes off at other peoples house.

I went to someones house that had a rack for shoes and another rack that contained loads of cheap slippers and you could wear some slippers if you needed to wear shoes. i loved this idea (athough i could see that this might gross some people out!)

love the matt idea - might have to do that myself - i hate people wearing shoes inside, i have polished floors and i am the cleaner and muddy footprints are just not cool!