My impression is that critiques of lesswrong mainstream positions and arguments for contrary positions are received well and achieve high karma scores when they are of very high quality. Similarly posts and comments that take lesswrong mainstream positions will still be voted down if they are of very low quality. But in between there seems to be a gulf: Moderately low quality mainstream comments will stay at 0 to -1 karma while contra-mainstream comments of (apparently) similar quality score solidly negative karma, moderately high quality mainstream comments achieve good positive karma while similar quality contra-mainstream comments stay at 0 to 2.
Do you share my impression? And if this is the case, should we try to do something about it?
I haven't done a solid survey, but I don't share your impression. I frequently see contra-mainstream comments get 6 or 7 karma; I also upvote them myself when I think they're well done.
Another influence that may be confounding your observations here is that comments with scores below -2 get automatically hidden.When is a commenter most likely to look at buried comments? Quite possibly, when there's an argument over the validity of a mainstream position going on. This would lead to bad contra-mainstream comments getting looked at and downvoted further even after they're buried.
You say:
The OP says:
...and yet you frame this as not sharing the OP's impression, which confuses me, because it sure does sound like your impressions are compatible.