Here is a good read...
http://www.cleveland.com/metro/index.ssf/2013/04/horseshoe_cleveland_fined_1800.html
Last summer, the Horseshoe substituted quarters for $2.50 chips that were close in color to $500 chips, causing dealers to make mistakes.
http://www.cleveland.com/metro/index.ssf/2013/04/horseshoe_cleveland_fined_1800.html