I would guess that the transposed letters are used to keep tabs on where their comments are live. It could look innocent, as if it were a human typo, but later

I would guess that the transposed letters are used to keep tabs on where their comments are live. It could look innocent, as if it were a human typo, but later the spammers could run a search and see which sites are trusting their comments in order to either edit them later or use their trusted account to post spam links.