There's a bunch of reviews for GOG games which are negative for reasons which are no longer relevant, ie criticizing no expansions for Dungeon Keeper, Syndicate, Wing Commanders, Alpha Centauri, etc, even though those games have since had expansions added. Also one of the top reviews for Dungeon Keeper 2 is essentially just saying about how hardware mode doesn't work for those with ATI cards, but GOG fixed that long ago.

I'm not in favor of deleting reviews btw, but some of these are just flat-out wrong.

I think the only way to fix this would be if GOG hired extra help to insert colored text replies right into those reviews, not at the bottom but right wherever a false statement was made, at least for the first couple pages of reviews. It's most likely impossible to babysit all reviews for all games but the ones up front need a bit more and clearly visible attention from moderators, I agree.

By the way, it's not only the negative reviews that can be non-constructive. It's equally unhelpful when, shortly after a game is released on GOG, people start posting flowery 5 stars reviews based solely on their memories about how much they loved watching their dads play that game 25 years ago and how magical it was to see those pixels move around, and then those reviews don't give you any info whatsoever about the GOG version.
I guess the blindly nostalgic reviews somehow balance out the angry negative ones so perhaps nothing drastic has to be done, after all.

I've seen one or two reviews that have had ***disclaimers*** placed at the beginning by staff to notify of certain changes or fixes. Apart from that, GOG's policy is to not moderate user content. This comes with both pluses and minuses.

yup I've seen some reviews with the disclaimer and some deleted ones because of racism like in The Shivah

I saw the Shiva one, too. Unfortunately, an "idiot detector" has not yet been invented. Guess it's the internet, after all.