I don't think generic comments are fake... how could they be, they're right in front of you. Probably a high likelihood they're an attempt for the poster to gain channel recognition through comments though. But what's one of the biggest recommendations on how to grow your channel... comment on other peoples videos. Sure, people who leave genuinely thoughtful comments because they liked your video not because they're trying to market their own channels are awesome... but with thousands of people trying to cross promote on YouTube at the recommendation of larger "marketing" channels, we're all bound to get them at some point or another.
...or maybe the poster could be genuinely unoriginal...
I'll gladly take a "generic" comment over the way it was years ago when the comment section of every YouTube video was full of vial hate-mongering. I say if they're positive, and not overtly spammy, publish them. The more comments you have the more comments you'll get. Just like views, subs, ect.