I have agree with you Styrak. Doesn't say much. Drywall dents and compresses VERY easily with regards to airsoft bbs. Heck, back in Calgary with AugMan, we had set up a 'shooting gallery' in the hall of his office once and accidentally took a few shots too high, nailing the dry-wall. Left some pretty deeeeeeep dents and thats it.
I'd say shooting drywall would be more of a show of force in regards to the power of the gun but has next to nothing to do with the bb or its quality. I kind of equate that to proving a bb's quality by shooting it at a pillow backed up by a few layers of cardboard.