I only slammed a yoyo, hard, on the ground two times around 1999-2000. Both were with my most expensive yoyo’s at the time, go figure…
First was my splash anodized Sb2. Had just finished telling someone how much it cost. Next throw. BAM into the concrete. It was loud! They said something like… “oooohhhh…that can’t be good… 
” It was pretty embarrassing at the time, kinda funny now. Only cosmetic damage to the yoyo. Although, that one broke my heart a little.
Second was a Came-yo Mondial, in the basement, string snapped, yoyo hit full speed into the concrete and bounced around the room. Major damage: multiple dings, bent axle…unplayable. Did get a new axle for that one eventually.
I definitely prefer yoyo’s without dings. Although, I’ve accumulated a few yoyo’s with scratches/dings and it doesn’t really bother me. soo… 