How was your experience buying Random Steam Keys?

The only site that I can recommend is gog.com. You know in advance which games are part of the event and they check your (gog) library so you don't get duplicates. Sure they are more expensive 1+$/key, but you don't end up with a double digit number of Bad Rats from your purchase.

I usuallly dont even waste my time with it, it doesnt take a genius to know that these are setup so that you would always get ripped off

here's the issue with those sales, and it's very similar to loot box issues, you are never told chances of getting one thing or another. If the chance of getting a AAA game is 0.1% then on average you need to buy 1k packs to get one AAA? it could be 20% or 0.001% we just do not know. Gambling with unknown odds is never worth it.

Usually got shitty games except ones where it was Dark Souls Prepare to Die Edition.

Got Titantfall 2 on GMG but also got a lot of trash...

Like a needle in a haystack and the Haystack being the shovelwares.

I didn't find a needle, yet. ^^