I agree with the neighbors: the color of that house is sickening.
I also agree with the homeowner: if there is no homeowners’ association, and hence there are no rules for the neighbors to enforce, he should be able to paint his house whatever color he likes.
Like I said, if you want to paint your house the color of your choice, be careful where you buy your house. Conversely, if you want to make sure all the houses in your neighborhood look essentially the same, again, make sure you know what the rules are before you buy. It’s really not that complicated.
The contents of this blog, this web site, and any writings by me that are linked here, are all my personal commentary. None of it is intended to be legal advice for your situation.