Greg was contacted not long ago by a casino who demanded he remove the scans of thier chips from his website. If I recall, Greg quickly complied so not to aggravate the situation... and that was that.

If you have problems with certain casinos NOT wanting their chips on a t-shirt or coffee mug, to avoid potential loss of money invested in pre-made products, maybe you could contact casinos and show them your artwork and get a letter of approval from them?

And on a positve note... if a casino denies you the freedom of using their chips, you'll have a great "illegal" line to market!! I can see it now:
BOOTLEG CASINO-WEAR! BANNED BY 17 TOP CORPORATE HEADS in 12 CITIES!!

... geez... just ignore me! I am going back to work