IT-I read it while house sitting when I was 20. It was very unpleasant.
Um IT was published in 1986 so reading it alone in 1990 had a long lasting effect.
Of course, I didn't like them before and add ventriloquist's dummies and puppets to the list of things that are uber creepy to me.
I also agree with PPs that even if I liked clowns, clutter and kitsch detracts from a house showing and will hinder selling.