You would see the regulars betting with the bad dice, and hence cutting in to casino profits. Could they do it at select or random times? Yes. But anyone paying attention or betting the trend would clean up and reduce the casino take.
IMO its way too much risk for little reward. I know in Nevada gaming officers make unannounced visits and will request all dice, cards, etc. for inspection.
I know a good many dealers and floor people at the local casino.....all they do is bitch about hours, wages, tips, mgmt, etc....If the casino ever told them to cheat in ANY kind of way they wouldnt wait 1 hour before tipping off everyone they knew.