In order to combat this, I'm thinking about changing the voting system to require a reputation of 30 to 50 before you can vote and / or limiting the number of votes per day to 2 unless you have over 500 reputation.
Hopefully, if these are not spam votes, the people making these votes (or wanting to vote) will leave comments on the maps first (to build up their rep), then come back and vote.
Before I make a change like this, I wanted to get some feedback, to judge if this kind of change is supported.
The idea behind limiting voting people with over (say) 30 reputation means the new members will need to have a few comments upvoted before they can vote. This should encourage some dialogue before being able to simply high and low vote a map.
Maybe making approved reviews should be a requirement so someone can't just easily farm rep so a spammer can't just make multiple sockpuppet accounts and upvote their own comments to spam? Or would that be a bad idea?