These are newbie accounts slowly generating activity and post counts and I've also noticed accounts like these act as a sort of "peer pressure" on new coin announcements and to bump them up organically. There was a funny incident once in the guncoin thread where Dabs's escrow announcememt was copy pasted by a bot (just a random pick i suppose) on the same thread, making it look like the bot was the escrow
Anyway, I'm not sure if this is an old issue that has always been there or something's that cropped up recently. Its a little hard to notice them because no one reads all the comments in all the threads. You might come across them by coincidence if you are following a few threads and the same exact line is dropped by different people. Just letting the mods know that there are bots among us
EDIT: Post history for above example bots are deleted by the mods