It would be nice if +1's were not emailed to all watchers as they add nothing but an annoyance. Instead convert the +1 to a vote which is, I'm sure, what the poster means to do but fails to see the "Vote for this issue"
Alternatively, place "Vote for this issue" right below the comment box alerting the user of how issue etiquette should work.
You win twice, no one get's spammed and issues have the correct vote count!
Now I need to unwatch this issue as I'm sure to get trolled with some +1's :)