Top three worst Dramas in your opion??

1. Time Slip Dr. Jin (korean)
2. 7th Level Civil Servant (only drama I finished, but regretted it)
3. Fashion King
(Dis-)Honourable Mentions: My Lovely Girl, Angel Eyes, Basketball, Super Daddy Yeol, Heirs, High Society)

and more!

1. BIG (time waster), Reply 1988 (replied by wasting my time with a shitty plot twist 18 episodes in that ruined EVERYTHING!!), Can we get married? (seriously who casted the female lead to read the scrip OUT throughout the WHOLE DRAMA!!) 

This thread just goes to show how ratings or even reccomendations don't make a drama great. Some of my favourites are hated with a passion by some users here, it's funny. I completely understand though. That's why I like finding hidden gems among the rubble of high-rated but often bland dramas.  The 3 that come to mind are:

Innocent Man (Nice Guy.) Don't even discuss this drama with me. It didn't satisfy me in any way. 
Pretty Man. Honestly, I didn't expect much. I don't even know why I watched it. I guess I liked Jang Geun Suk's character in You're Beautiful so I gave it a chance. But even David Choi (Lee Jang Woo) couldn't save this drama. I actually reached episode 15 (I watched it while waiting for updates on other dramas) but I couldn't even see the last episode...
Marry Him If You Dare. I watched it for Jung Yonghwa (CNBlue). It was okaaaay. But I don't think I would recommend it. It was disappointing. 
Bonus: Heartstrings.  This too I watched it for Jung Yonghwa (CNBlue). Other than to satisfy my fill of his cuteness, I'd never recommend it. 

I have other dramas that I would list, but I enjoyed them a bit at the time (*cough* The Heirs *cough*) so I feel bad listing them haha.

Secret Garden 
Hana Kimi (Japanese Remake) (I pretend it doesn't exist)
Flower Boy Ramen Shop (I don't actually remember how much I dislike this but it's rated pretty low which I don't do very often)

Cheongdamdong Alice
High Society [Don't kill me! Never would have finished it if it weren't for the second couple]
Pretty Boy

So far.. I think I don't have to mention Pretty Boy, Playfull Kiss.. and such dramas that are obviously ridiculous and plain.. Absolutely not to everyone!
I'm gonna choose the worst dramas I'm holding a grudge against because either they have my best actors/actresses and I think they were half asleep when they signed the contract for that drama, or because my hopes and expectations for it hitted the wall ...
Top1 Drama I hate the most:
Remember: War of the Son, yes ..! I'm tired explaining my anger towards this drama's author... I won't say anything, you may know already why I hate this drama if you've seen it.
Top2 Drama I hate the most:
Doctor Stanger, again, that was definitley a fantasy, not a medical drama.. not to mention its ending that made me feel like.. a victim, a fool!!
Top3 Drama I hate the most:
Mask, that drama was good, actually, veery good, until I don't know when the author started making some unreasonable mistakes.. especially the last two episodes, they were a mess that made me regret watching the whole drama.

There are others of course but those above are the dramas I hate the most.. and if u check my drama list you'll find me rating them a 7 or similar .. That's to be fair because I enjoyed doctor stranger and mask at the beginning.. but I won't recommend them to anyone.

Well, I'm 50/50 about Playful Kiss, I like some parts of the story but I definitely can't with the personalities of the main characters. For Heartstrings, I liked it actually, especially the music, but I hated the line romance btw Min Hyuk and Woo Ri... Anyway, for me were 1. I Do, I Do, it's boring to dead! Hahaha I finished it because I can't just drop the story, but this is the worst drama I have ever seen xD 2. To the beautiful you, another boring predictable drama. 3. Pretty Boy, BoTong is like a worse version of HaNi.