One problem is that it's very easy for bidbots to deliver votes in a less transparent way, it can be delivered through a network of sockpuppets, then it's very hard to blacklist the voters.
One possibility (which should be possible to implement relatively easy on a centralized web site) is to multiply the vote weight with user authority score rather than voting power. That would most likely cause a trending-list that would not significantly be affected by bidbot services. (the problem with that is that user-authority currently seems to be a closed-source black box).
Part of the issue with user authority is that it is rooted in the witnesses own activity as the basis for the score. Who witnesses follow gain greater authority. Several of the witnesses run major bid bots.