I definitely see these more as a promo tool that anything else, although I do tend to only bid when I have a positive ROI, I do think the bots are so popular now though that I really just stick to Smartsteem. Occasionally you do get a good opportunity.
One other way I saw someone mention once was to use the bots like a 7 day futures contract for increasing ROI. Essentially you are giving the bots one SBD today. Since the price of SBDs fluctuate if you think it's going to go up you can buy SBDs now the the votes and get them back in 7 days at a higher value! It also work the other way too, so you should probably convert your SBD to STEEM instead if you thing the price is going to be going down...
That's a great way to think about it adding value to the ROI!! Super excellent point and I'm so glad you mentioned it!