Steem blockchain has been designed to incentive the good curation. If you upvote a post which has low value and time later it becomes popular, then your curations reward increase. Next Vote is an App that shows you a list of posts that will receive a good vote from a Bid Bot.
Suppose you upvote a post, and after that, it is worth in $2. If this post finally goes to $100 then it scaled 50 times after you. The root square of 50 is 7.07, then your curation rewards scale 7.07 times. The advantage of the bid bots is that we can know which posts will receive an upvote and at the same time its approximate value. If we choose posts that will scale a lot, so will our profits increase.
The actual development scans all bid bots and the current round of each one in order to show a list the posts that will receive an upvote. It is based on the bot list provided by Mattylce - bottracker.