I don’t like it though when people diss their own songs, because it’s basically insulting the people who do like the song. Best to just keep those opinions to yourself.
Depends on how they say it, but yeah it can leave a bad taste. In Townsend’s case I find it amusing, partly because the songs of his he thinks are great are complete turds (like English Boy off whatever solo album that was). It’s funny to see how one of the greatest songwriters of his generation actually has no idea what makes a song good.