I know some people have really taken on board the idea to reward people who comment on their post, to the extent they probably upvote any old shit comment.
I've seen some spammers get more rewards for their two word "beautiful post" spam comment than their one shit image post.
I've seen some spammers get more rewards for their two word "beautiful post" spam comment than their one shit image post.
It's up to everyone to judge what they dish out in comment rewards.
This is about post rewards though, not everyone has the ability to give out comment rewards due to insufficient VP and I would advise those people not to comment vote, but post rewards stack up and even the smallest voter can add something.
I upvote people who comment on my posts but it's always calculated. There's less and less I want to vote out there these days so I often spread large upvotes around to those I know well or who engage with me in meaningful ways; it says, thank you for taking the time to have built a relationship with me and then to nurture it along.