There's a saying that goes: one man's trash is another man's treasure. What's a good drama to me might not be a good drama to you. Every drama addict (and non addicts) have their own standards in judging the quality of a drama.
I tend to look heavily at storyline, acting, and chemistry among the cast. Those three elements are most important to me when deciding whether a drama is good or not. Ironically though, they are not the first elements that attract me to a drama but two of three (storyline and chemistry) are key factors that determine whether I will continue a drama. I can forgive bad acting...depending on how bad it is.
The Celsius Estimate Theorem
Sadly, the amount of time we use to watch dramas is precious and limited. We simply don't have the time to sit through every single drama. We have to use our time wisely and choose the good dramas to watch. I'm sure every drama addict has their own way of choosing good dramas to watch. If you don't have one yet, that's ok! You can use the Celsius Estimate. The Celsius Estimate works 90% of the time and it estimates if the test drama has potential to be a "good drama".
Method of Execution (Go in order):
1) Watch the first two episodes: If you enjoy the first two episodes, keep going. Otherwise, proceed to step 2.
2) Watch the last two episodes: If you enjoy the last two episodes, then consider watching backwards or start watching from a few episodes back. Otherwise, if you hate the beginning and the you hate the ending, you'll probably won't like the drama anyway so move on to the next drama.
3) Optional: For more accuracy, choose a random episode in between the first two and last two episodes.
This method is no guarantee. You might miss a good drama or the test drama turns out to be a bad drama despite an awesome beginning and an awesome ending. But nevertheless, it will give you some kind of solid ground to stand upon.
So use and adjust at your own risk!
Thanks friend who forced me to realize the flaw of my theorem