How do people here define over leveraged?

[Adam Sporinsky]

In many of the BP podcasts, articles, and blogs, the idea comes up frequently that people who really have major issues during donwturns or in RE investing in general are people who buy wrong (pretty clear I think), or people who are over leveraged.  For instance in the it comes up in the Grant Cardone episode when Brandon Turner points out that if you buy right it's very hard to lose money.  Grant responds that Brandon should meet some of his friends, who Grant says were over-leveraged and that that was what caused their problems.

The discussion I would like to start here is: how do the successful real estate investors here define over-leveraged?  How much leverage do people consider too much, how little reserve do people consider not enough?  What are some ways to become over leveraged or how to determine if you are, either at the time or before a deal.  If someone does become over-leveraged, what are ways people have solved that issue?

What are the best practices on amounts of leverage and reserve cash?

I think this could be very beneficial to people who are starting out, but also to people who have been doing this for a while.