I interviewed at Google. I passed the phone interview. I did an in-person interview. They told me I was "not a good culture fit" (i.e. I'm too old but they can't say that).

Then they contacted me a few months later and asked for another interview. I said no.

Then they contacted me a few months later, again I said no. I asked them to put a note in my file and exclude me from further contact. So far, that seems to have worked.