It's important to calculate with a voting bot if it's going to give you a good return on your investment.
I don't think there's anything wrong with using them necessarily but I do think that sometimes you don't get as good of return as you might expect.
Indeed, are they Resteeming? Are they upvoting? If so are the followers "dead" followers ? What about curation rewards they are reaping from your content? Do they incorporate this into the price? How do we determine what the best bots on steem it are ? How often would you use them ?