The houses are haunted (1)
This is a possible critique of the boredom of suburban, middle-class life. It's spooky, and it's meant to be. We're scared for these folks, who might be harmed by their own boring conformity.
By white night-gowns. (2)
The white nightgown may be the least sexy bed wear, second to flannel pajamas. Nobody really sees what we wear to bed except our families, so why are we afraid to wear some wacky stuff to bed? Hopefully, unlike the people in the houses, we can be our creative and unique selves when we are at home without fear of being judged as strange.
None are greenOr purple with green rings,Or green with yellow rings,Or yellow with blue rings. None of them are strange, (3-7)
After pointing out all the things that aren't there, the speaker has left the reader hanging on every word to fill that absent space in the reader's imagination. The space is like a vacuum that wants to suck in the next creative image that it can find. We're starving for a good metaphor by this point, because all these awesome colors are being repressed.