There's no real way to tell if an asset pack is decent, but there is a way to tell if it's NOT decent:
If they have an AI write marketing dross.
I remember a decade ago, I would have just presumed they were Russian or something, and chalked up bad writing to the language barrier. Now it's always just AI.
If you use AI on the The One Thing Literally Everyone Will See First, that doesn't make me confident about the quality of the rest.