Since introducing the voting system, people are still +1'ing the issues they like. This is annoying for anyone watching said issue and receiving these +1 emails, it's noise in the presence of real & useful comments, and it doesn't help raise the visibility/priority of the issue from a "votes received" perspective, which is the purpose of voting.
I propose we convert all existing comments with only the content "+1" (accounting for white-space trimming) into votes and remove them. Also, any new messages with just "+1" would get the same treatment automatically.
If any of these existing messages have replies to them (which is rare AFAIK), then we should probably keep the original message for context, but still add their vote.