American Taekwondo Association with its 800 locations in the U.S. is the king of all the McDojo's. 18-24 months to blackbelt with them is ridiculous, and after that amount of time, those blackbelts perform no better than a green or blue belt elsewhere. Also, they copyright all their forms and techniques, and should after blackbelt you quit them, you can't show what they taught you to anyone else, for fear of lawsuits, making your knowledge useless. Look in this dictionary under ATA for more info.
Bill Clark's Schools, Richard Reed's schools, Robert Allemier's Schools, the list is endless of ATA multi-millionaire McDojo owners who put money and contracts before creating quality 1R's.