I think for Jazz, Flamenco and Classical they are really good, especially the GS and PS models. I cannot speak for other genres. Definitely not headphones with subbass, so suitable for some types of electronic music.
In my view some models are a good buy in the used market, such as the GS1000, PS500, PS1000, RS2e, and also some brand new models such as the 325x and RS2x. Admittedly I would not pay more than 700£ for a Grado.
I am under the impression that they do not pay for sponsored reviews on YouTube which may contribute to hearing less about these than others. Some Youtubers I generally trust like DMS had a very positive review of the SR325X and so did Brent Butterworth on Soundstagesolo in regard of the RS2X, to mention a few. Steve Guttenberg also reviews them very positively.
Then yes, you get Youtube promoters like J. Valour who spits on them fake reviews, possibly because he approached Grado for a promoted review and was snobbed...