Yes investing in upvotes will generally give you a negative direct ROI, however the idea is that if you can get your posts on the trending page then you will get more visibility and more real upvotes and followers which should give it a positive ROI overall, although indirectly.

I will check out @bellyrubbank, haven't hear of that. Would be good to create a site that lists all of the different bots and services running on Steem!

I looked into cloud mining but didn't want to make the investment - glad it's working out for you!

Funny you mention it because I am actually working on my own bot right now. The issue with making my own upvote bot is that for it to be any good it needs to have a lot of SP which I can't give it right now. I have a different idea though which I will post about when/if I ever finish it, so stay tuned!