I have also witnessed this and one particular scammer sent my blood boiling mad! It was a similar incident where a writer had written a very personal piece and the scammer had commented with the same insensitivity and begged for reciprocal readership. I replied to the comment telling the scammer what I thought of their behaviour, and yet i'm sure it wasn't even noticed because these scammers don't comment for engagement or to support other writers, they come for the misguided idea that they can get rich quick.