Yes, whereas I think the concept of MS/GS is a useful one, I think it can lead to lazy reviewing.
I don't like OCs as a general rule but I'm a canon purist to a large degree, so my hackles go up automatically and often I don't give them a fair chance.
I was once accused of MS-dom by a beta. It still mystifies me as the evidence for her so-called MS-ness was in canon and she was OBVIOUSLY mentally unstable.
Boy, I can bear a grudge.
The Harry-Sue-ness, I get that. Harry actually bored me up until OotP.