A senior student in my dojo once said he looked for two signs of a "healthy" dojo:
1. A place where students being taped up, bandaged, or off the mat for injury was a rare occurrence.
Wow... our dojo must go through un-healthy spurts then, because for a while, just about everyone was taping up a wrist, foot or something. We have two people sitting off the mats right now, but one of the isn't a dojo related injury. My injury was purely accidental. Things happen sometimes unfortunately.....