My main problem with dramas is that I most of the time get sick of them once the main couple gets together. Usually, after that if the show goes well it gets a dumb extension that adds nothing interesting to the plot and completely ruins it for me. Some other times, it's the acting/lack of chemistry.
Bridal Mask (More like the king of unnecessary extensions, amirite?) I liked the story and the acting was superb but I found there were a lot of characters that offered nothing to the plot and wasted screen time.
You're Beautiful: This drama had potential but I can't help but think that it was made for 5 year old kids. I can't wrap my head around it. Also, I didn't like either part of the main couple so I was really glad when I finished it.
Faith: I'm not sure if it's overrated or it's just because LMH is in it so EVERYONE says it's amazing but I put it on hold halfway through it like 3 months ago and finally got to finish it last week. I only did so because I was curious as to how it would end. ( ._.)
To The Beautiful You: I only wanted to give this a shot because it was popular and Sulli was in it but I can't get pass the first three minutes and I've tried 6 times already (yes, I've kept count.)
Monstar: ????? ?? ????????? ?
For me it's Heirs and Masters Sun Also BOF
Also Secret Garden. Everyone likes it but i find it boring.
Boys over flowers-pkayful kiss
You're Beautiful - tried to watch it a couple of times but just couldn't get into it. Heirs - watched it because LMH was kind of cute as Kim Tan but it was badly written, directed and acted.
My Girlfriend is a Gumiho was boring, it started out good but turned into a drama mess, i was so disappointed Reply 1997, they tried to play up who the daddy was bit way too much, then the older brother with the lead girl was weird idk not one i would recommend King 2 Hearts, i was sooo disappointed because of who the leads were, i adore them both but the story was all over the place. i loved the princess and the body guard story, but the villain was insane and the focus of the drama was unclear Shutup Flower boy band, so over rated it makes me sick, i watched it while it was airing, the first couple of episodes were good but then it just got boring and ridiculous idk why it was ppl rated it so high. Innocent Man, a close friend and my sister said they loved it "its so good..blah blah" I watched it and waiting for something exciting to happen, the acting was amazing but.... ugh so overrated. I love Song Joong Ki and Moon Chae Won but this doesn't have any rewatch value.
Let's see. . . there have been a couple. To the Beautiful you - I actually regret not dropping this one. My Girlfriend is a Gumiho - I wanted to love it, but I got incredibly bored. Playful Kiss - Oi. Lie to me - Started out pretty good, but the last few episodes DRAGGGED. Full House - Again, the first few episodes were pretty good, but the last 10. . . I could have sworn I was watching the same episode over and over again.
For me it's Coffee Prince, Gu Family Book and Secret Garden
My Girl - Lee Jun Ki is the only thing that is worthwhile about this drama. I'll admit it, it was funny at first, but once the humour went the drama lost its sole crutch. The characters were thrown into these ridiculously over exaggerated situations that led to a ton of plot holes and loose ends by the time the drama actually finished (the connection between Lee Da Hae's character and Lee Dong Wook's missing cousin was never explained). The female lead became so annoying, by the end of it, that I just wanted to push her off a metaphorical cliff. How did she go from being bubbly and sly to being a wet wipe? 

The Greatest Love - Yet another Hong Sister's drama (really do not understand the hype surrounding these two). Couldn't even make it past the first episode. Humour is desperate and juvenile. Gong Hyo Jin's character is just a waste of space. 

Full House - It's definitely funny during the beginning, but the drama falls flat once the romantic feelings start to come into play. The main leads were in denial for an excessively long time which led to a string of repetitive will-they-won't-they scenarios. Also, the main girl is the world's biggest push over ever. She welcomes her scamming friends back into her life after they literally took everything from her - I think once they sold that house, they also sold any sense of pride or dignity (if she ever had any to begin with) with it, because if I was Song Hye Kyo's character I would have reported this two criminals to the authorities once I got my ass back to Korea. Finally, Rain's character as just a dickhead - don't know what she saw in him

My Name is Kim Sam Soon - It isn't bad, but it certainly doesn't deserve the immense hype and praise it receives. It is just another boy-meets-(slightly older) girl story. The characters are polar opposites and never seem like they should be anything more than friends. Hyun Bin's character has no sense of loyalty and faith, and to be honest he's a bit of a sleaze. Sam Soon spends way too much time whining over petty and frivolous matters, and for a 30 year old woman with some life experience under her belt, she sure lets herself get easily dominated by some punk. Who cares if she can cuss when her words are empty? (Oh yeah, and that open ending was frustrating.)

Goong - Cut out the unnecessary drag and it would be worth an 8. Shouldn't have ever gotten an extension because it made the plot wear thin.
I'm a fairly easy person to please, so I'm usually not surprised by things being rated highly. However, anything I've completely dropped I think are over-rated, like 49 Days, Love Rain, The Heirs (which I couldn't make it through the first episode let alone the whole thing), Queen In Hyun's Man, Incomplete Life (which was a bit upsetting because I was really excited to start this one). Then there's a few things I have on hold that I don't know if I should bother to finish like All About My Romance and The Moon that Embraces the Sun, both of which I was incredibly bored with.
This is basically a list compiling of all the dramas I began with because I didn't have any access to MDL at the time, haha. Boys Over Flowers, Coffee Prince, Secret Garden, Playful Kiss, Heartstrings, Personal Taste and lastly the more recent The Heirs. Well, when it was airing at least, I know it isn't particularly popular now. 

This just reminds me of how much I need to go though all my ratings on my list because most of them are now inaccurate, gah. Let's go do that now...
Okay for me You're beautiful!!! Like really...? I couldn't even finish it even when i love gender bender...but my mom loved it so idk....
Another drama is Playful Kiss but not ALL! I am just very dissapointed with ending so only ending is bad...
Hmmm then BIG 
Bel Ami definitely...idk even if it's popular but if yes then it's totally bad!!! 
DREAM HIGH 1 & 2 are the most horrible overrated dramas i ever saw...or couldn't finish better said...i just hate it blaaaah 
High school love on 
And of course HEIRS!
Mater's Sun, the lamest act I have seen, still wondering what's the fuss about that drama.
Inspiring Generation, another pile of wannabe actors.
Every drama with Park Shin Hye, I think that producers should start giving roles based on acting skills, not based on the looks.
Healer
Kill Me, Heal Me