I have disposed of all my non-Apple MacBook Pro chargers I have scattered around the house after watching the teardown videos a couple years ago. I happened to come across another one that was stashed away (one of the Chinese clone you find on any websites), and I decided to run a test to get some quantitative numbers.
While charging my half-charged MBP with it running and engaging the high performance GPU, the charger exterior skin managed to exceed 183F at the center of the charger. The charger is propped up and only the narrow bottom edge is touching the floor. At this rate, you can easily get a burn by touching it, and I wonder if it even have a temp cut-off safety feature if it ever falls between two couch cushions. So it is definitely destined for the garbage can. If you have these chargers, heed the warnings that many have posted, you never know what you get and it is much better to buy a replacement directly through Apple.
The weak link on the Apple charger is the cord, I have been through three of them due to defective cords. Now, I would desolder the cord on the clones before tossing them, and that would keep my original Apple charger working for a couple more years.