I don't think it's half bad to be able to buy a vote that will make a little more value than what was paid.
Being a small account, a few times I have used a bid-bot to purchase a vote for a post I felt deserved more than my vote could give it. (at 100% I still give a dust vote).. If I am bidding to only get a vote worth the same, I may as well have just transfered some STEEM to the author. I appreciate there being a service that provides a little more value for my value..
I do think that vote rounds should be a 24 hour cycle, and allow humans to look over the posts that have bids placed, and then 'vote' yay or nay on if the post deserves the bot vote.. majority rules - and the bid-bot owners - could set up a white-list on who's 'vote' counts towards.. the vote xD
But I know that adds a lot of extra work and don't expect anything like that to be implemented. It's a hybrid of manual curation and bot curation I think though, something I think should be explored perhaps in the future.