I see lots of articles touting the benefits of meditation. But what are the bad things about it? Maybe if a person has to make quick decisions, meditation would not be a good thing? This could be similar to a paridigm of "Thinking Fast, Thinking Slow" by Kahneman.
While meditation is used to prevent depression relapse, meditating while in a depression or overly anxious is not recommended. It can make things worse. (I am assuming here that "meditation" means "mindfulness meditation".)
I remember someone saying that for some very anxious people becoming aware of one's body only make them more anxious because they fear their body will fail them. I believe this is from French psychiatrist Christophe André, although I've not been able to find exact source. I'll try again later.
Another source: http://www.wildmind.org/applied/depression/when-not-to-meditate
And this is from the Mindful Way Workbook: