I usually bot game Dominion for my FWOTD, and I have seen I few obvious bots. Move and attack randomly, oblivious to obvious danger (hmm 3 bots are coming right for me, better sit here and AA minions), buy random items and random summoner spells (often no boots, Ashe with a giant's belt, tear, and pickaxe running smite, etc.), don't respond to anyone or anything even when I say, "If you aren't a bot, please say something or I will report you for botting.".
They definitely exist. Make it clear in chat you suspect them of being a bot, and encourage your team to report them if they don't respond to anything so tribunal gets an idea of what's going on. Don't think it's done for IP mainly though, most of them have been sub-30 accounts who probably got their main banned and are trying to grind out a level 30 account again.