I have do some research on how people using bidbot to earn money. I have random select 5 spammers with shit contents and count their ROI. Some spammer can earn more than 260% ROI with their rubbish posts.

The main ROI is come from the people who love to blindly upvote the post in trending page.
(Just using Bidbot with little amount of SBD could not make sure you can have positive ROI.)

You can check my result here.

Spammers are using bid bots to earn extra 160% SBD with every shit post!