Those people make me very suspicious, and they come out of the woodwork at the start of every campaign. Their posts look like "I will NEVER support ANY candidate who voted NO on the [insert issue here] because they are not real AMERICANS, and the only REAL candidate here is [some third party yahoo]" blah blah blah (feel the fury of my CAPS LOCK!). I remember someone back in 2008 who was angry that McCain was winning in the primaries. He said that he would never vote for McCain even if he became the nominee, and that it would serve the Republicans right if Obama won. Maybe the party would come to its senses, or something.
I have always suspected these people of being Democrats who came here to cause trouble. They plant the seeds of dissatisfaction by suggesting that it might be better to "send a message" by not voting at all. or they try to convince us to vote for a candidate who has no chance of winning. It might be worthwhile in some cases to investigate their history here to see if there's a trend of poking the hornet's nest. If they're not Democrat operatives, then they are probably simple trolls, not worth a reply. If they are just trying to get a rise out of someone, ignoring them will cause them to wither and die.