Want a more objective measure of overowned/over-loved any stock is? Look for companies that have these 3 characteristics:
1) More than 90% institutional ownership;>>
2) More than 90% Buy or Strong Buy;
3) 1000% gain over the prior 3 years.
I attended an Investor's Business Daily CANSLIM meetup recently. There they use the term Climax top as a technical condition. They loosely define a climax top as occurring at least 18 weeks after a proper breakout from a base, with a quick additional 25% to 50% gain. Some use the adjective parabolic to describe the chart. Climax tops can also occur in commodities. The 1980 precious metals peak was an example. The more recent move to $49 in silver might also be loosely described as such.
Using either set of criteria, it can be difficult to time the exact top. However, it gets extremely risky to be long, when a stock becomes over owned, or when it goes parabolic. It is tricky to try and short it as well. Often times, better to wait until after the first break and short the rally attempt.