My Drama List rating scale: 

10 and 9: my fave drama that was perfect for my own personal taste & mood. 

8: great drama that kept me entertained until last episode. 

7: good drama that just didn't have that special "spark" for me or had something that bugged me. 

6: drama that had the potential to be good but didn't live up to it or had a few elements that bugged me.

5: drama that was very basic or had too many "what?! why?!" parts to get a 6 rating. 

Anything below 5: drama that was bad /a waste of time for me.  highly probable I skip-watched to finish it because someone I find cute was in it or was curious to see when the bad will reach the worst  :-)  

Anything dropped: drama i tried to watch at the wrong time/wrong mood, got boring/draggy mid-way, i couldn't care about the lead characters enough to keep watching, or was simply too bad for my taste. 

Movies: i never rate them.