I have used bitbots with the strategy outlined in this video:
Using this strategy, I had a positive return on investment of about $3-$4 with every post, as opposed to only 50 cents or less when not using it.
However, that wasn't the main reason I used it. In my opinion, the only justifiable reason to use a bidbot is to get your post to the top of the "trending" page for a particular category on Steemit.com. In theory, this should get more eyes on your writing, which could translate into more "organic" upvotes (upvotes from people who genuinely like your writing, not from people whom you paid).
This seems to have worked in my case because I did get a lot of upvotes from people other than the bidbots. So the extra "advertising" seems to have paid off. This might be similar to the way you can get more attention on Facebook by "boosting" your post.
Despite this success though, I was disappointed that it didn't lead to more followers. I was willing to keep paying bidbots for many months if it meant that I could eventually get enough followers to do without them. But it didn't seem to be working in that sense. And $3-$4 is not enough money to justify spending four hours writing an article. So I stopped doing it.
In fact, I decided to stop posting altogether and focus instead on curation.
One thing is for certain: I experienced no fallout or social ostracism of any kind from using bidbots. No one flagged my posts or even made negative comments.
As for whether you should use it, 
To summarize: I think bidbots can be helpful if you are new to Steem and have no followers. After all, it's hard to get people to upvote your posts if no one can see them. But they also can't help everybody. Some people just won't get followers no matter how much exposure they have. And some people already have followers...in which case the bid bots are probably a waste of time.
RE: Using bots for upvotes - have you done it?