His site does show when the bots are showing a positive ROI. In the final ten minutes they turn green. Also popups come up for profitable bots. But I don't believe there is a filter to filter out neg ROI bots. You can however see which ones are neg as max suggested bid is above 0.
Trouble with having only positive ones show is that pretty much all the bots that are more than say 20 mins from voting show a positive ROI and then people come in toward bid time and reduce your profitability.
In the actual bot he created he put in a min ROI setting where the bot owner could stop taking bids below a certain ROI.
Some say the bots are to gain visibility. Ie upvotes = more chance of being seen. Not to make a profit. Ultimately the culture of STEEM is about creating quality content over simply going for cash.
In any case the bots face the issue of if their vote pool doesn't fill they ... don't lose money per se but they get less than their vote value
Hello peter thanks for your reply. as @therealwolf mention there is a column where you can see negative ROI limit and some boots have a 0%, I guess if you bid you are certain to receive a fair vote back.
If the bots are fair with their user they will be used more, if it's the opposite people will stop using them. You can see on the Steem bot tracker page, most voting bot have no negative RIO limitation.