Are bidbots profitable?

Bidbots are used for post promotion activities. Use of bidbots can increase your reputation score as well as your chances of earnings.
Only bidbots cannot make your post profitable. In fact, investments in bidbots can be result in a loss if no generic votes are received on your posts. I observed following things while using bidbots:

If after using bidbots, the price of steem goes down, then the use of bidbots will result in a loss.
If after using bidbots, price of steem rises, then the use of bidbots can be profitable.
If no generic votes are received on a post, then the use of bidbots will bring a loss for you.
Bids should not be send at the last moment because many users can send bids in the same way. It dilutes the voting value of the bot. Also, bid should not be sent if the bot has received 90% of the maximum profitable bid.