[somewhat solved] filter out the trash games

And you want to accomplish it how? Even trash games got dozens of hired fake reviews, so ratings doesn't always mean anything.

Many weren't lazy enough and single handedly filtered them out themselves one by one.

This is a suggestion the site owner will absolutely do nothing with it.

Blacklist them.
On my BL is 30,228 games. Yes its annoying but at least something.
On my "all" tab is 8 games. Nice clean SG.

Nobody (SG) will filter them.

There are many trash 50p asset flips that have positive reviews because of hired reviews. So it wouldn't help much

Are you aware that SG has a built in function to ignore games you don't want to see giveaways of? It's what ScetCZ up there is referring to as "blacklist them". On the front page or the giveaway page itself you would have to click the rightmost icon next to the game's name: it's supposed to depict an eye which is crossed out. You will no longer see giveaways for the games which you put on this personal ignore list.
This list can be managed by clicking on the cog icon on the front page to the right where all giveaways are listed.

You may find it useful.
Try this link to show only games that have a metascore rating greater than 85%. Change "85" to whatever rating you want.
You can also set other parameters.

I block them individually myself but it doesn’t help much when there’s a thousand new ones every day

If you are looking to discover games actually worth playing (not necessarily being given away atm), you can check the community wishlist:

https://www.steamgifts.com/giveaways/wishlist

There is an option at ESGST which lets you sort and filter games by their Steam rankings.... This is not sure-proof (hm, is that even a word?), since many trash games have fake reviews which give them ratings near 100%, but is is a good start.

Steam ratings aren't the best tell of what's good and what's not. Games that where made for pure money (asset flips, trash, etc) will pay for good reviews, and there's many fantastic games out there with either very few reviews, or review bombing/troll reviews/kids refusing to realise what the review system is (so many times I've seen "I loved this game, but I think the overall rating is too high so this is a negative review to bring it down").

There's also this: https://www.steamgifts.com/giveaways/search?type=recommended

just hit the ignore. they usually come in waves. also most multicopy giveaways are trash so start there

If you see a trash game, chances are the person who created the GA created another 50. That is usually a good opportunity to ignore them all at once. One user created something like 30 of those 8 hours ago, valid for another 16 hours, so you can already target a lot of those in one go.

While you could also potentially BL that one user to prevent these games from showing, up nothing prevents other users from posting the same games, so ignoring them feels to me as a better long-term option

I've spent a little time here and there in the past couple years, to increase my hidden games list to almost 2,000 at his point.
Although some blacklist people who give nothing but garbage, i feel a bit unsure about it, but have slowly stared to notice some users literally give nothing but garbage, and black listing the ones that have given away hundreds of low value games, is probably the best for the community.

Only other thing i do is increase my wishlist, which helps smaller indie dev's and doesn't really effect anything negatively, as you can go in and prioritize your list, and leave all the early access/indie titles you're keeping an eye on, down at the bottom.

Some people get annoyed at people having a large wishlist, but i dont really understand why?