I have seen votes at 0.7%! What then happens is that people follow the trend, not realising how it all works.
If a vote does not register it goes into a dustpile which then gets distributed back proportionally to the holders of SP - thereby handing even that lot to the top 100 or so. I have seen tiny minnows voting at 5%.
There is a counter argument which says, as your vote is worth so little, all that matters is that people see you voted for them! So, with a vote worth $0.0001, what's the difference - vote like crazy and see if you can pick up some followers.
Personally, I would ban it. But ... I just know where the system is heading.