I've got some MOFI 1/2 speed LPs I bought back in the late '70s ~ early '80s, They're very good, although you have to turn up the volume to get to the same SPL.
Also have some of the newer 180, 200 gram LPs that are super clean sounding, and seem to have a deeper, more complex sound.
On the other hand, most of my older LPs sound quite good as well. They just needed a good cleaning.
Of coarse there are some that were just plain mastered wrong, like the infamous hole in the middle recordings that have nothing common to both channels, thus no phantom center. Or others that have the singer's voice in the middle but all of the intruments to one side, those really sound stupid.