I see a huge difference between a bot that exists to drive losing bids from users desperate for attention and a service that allows regular users to buy votes from others at a discount. (Smartsteem is a bidbot though. Smartmarket isn't.)
If you were to change it to "paid upvote bots" you wouldn't get that complaint from me anymore. I have plans for the letter game though.
The paid upvotes is a great, but I fear that authors who received the votes when someone else paid for them will then object.
I may float it and see if it sinks.
Blessings!