It is cheating, in a sort. I've used them before because I see it as the only option to get some content noticed, but after doing the math, I end up losing SBD that I'll never get back. But it is the only way to get your post in the trending page, and I've only seen one of them there once (Ghost Trick, if I recall).
Was it worth it? Probably not. But it's a way of getting some SBD back and the all-important Steem Power along the way, instead of just investing all in SP and being left with nothing.
Accounts with tons of SBD don't have these dilemmas, but others do.
Bidbots need some serious refinement, and I'm glad to see some of them already working on it, such as @smartsteem, which blocks spam accounts from voting. This is the future, every bot needs to do the same.