It might be better to say "if a school cares too much about getting new students' money, it may be classed as a McDojo".

If they're neglecting other costs to spend on advertising, such as not purchasing new equipment or not repairing damaged equipment, it's likely a McDojo. Basically, if it seems that their primary aim is to get new students to pay them, you should be wary. You may be able to find just as good quality instruction elsewhere for a much lower price. The whole McDojo issue is very subjective so use your best judgement. If you can't decide ask for other people's opinions on the Dojo, or ask on these forums.
Self Defense
(Website by Marc MacYoung, not me)