Boys Over Flowers (the korean one)
Yukan Club
Hanazakari no Kimitachi e (all of them)
Zettai Kareshi
Boysitter
You Who Came From The Stars- Why? just why? Is society going back to the old Prince Perfect Charming idea? 

My Girlfriend is a Gumiho
- So many fails. 

Kill Me, Heal Me- Ok I loved this one BUT it's only because the male lead stole the show. He made it worth it.
Another City Hunter one here. Also Sungkyunkwan scandal bored me to tears. Loved my actor bias song joong ki but that's about it lol. Another i wasn't impressed with was reply 1997 but i'm not a big fan of flashback dramas
Coffee Prince
You're beautiful
1. Playful Kiss (characters were just plain annoying)
2. Heirs
3. Boy's Over Flowers
4. You Who Came from the Stars (this one was alright, but I don't understand why it was so popular)
5. City Hunter
6. Master's Sun (this one I like the most out of the overrated ones, but I still don't think it is as good as people make it out to be)
*lol I guess I don't like Lee Min Ho dramas
iris - no chemistry for me, the story is so-so, and the candy kiss - sweet? c'mon, it's disgusting for me (no offense, that's just how i felt) 
Hotel King- girl is just ughhhh
Healer-boring,I figured out the mystery by episode 9
That winter the wind bows- couldnt take the whining and crying anymore and I dont get why everyone loves Jo In sung he was expressionless in this...
Boys over Flowers & Heirs --these two are the very definition of overrated. Sure, some enjoyable and entertaining moments in each, but they are waaaaay too hyped and they seem to permeate everything related to k-drama. There is NO ONE who is into kdramas who hasn't heard of these two. Overrated for sure.

I also think Secret Garden is the same way. I genuinely liked that drama (at least parts of it), but I think it definitely falls in the overrated camp too. 

Oh, also Faith. ....I watched the whole thing, hoping to understand the love for this drama. It was just bad. I don't know why people like it, I found it boring most of the time. 
Boys Over Flowers ~~ really? really?.
Heirs ~~ its like " Lets gather good looking actors and make a drama" and poof its overrated.
Oh my /ghost ~~ i like Park Bo Young and Seulgi is amazing but...its loosely from Arang and the Magistrate. Secondly, the possessed Bong Sun is like a different person from Sun Ae. Chef's true love is Sun Ae.
BOF, Playful Kiss, She was pretty, Doctor Stranger, The girl who sees smells, Cheer Up, Reply 1997, Kill me heal me, Secret Garden, Empress Ki, Sungkyunkwan Scandal, You're beautiful, Coffee Prince, You Who Came from the Stars...

I enjoyed some of them but I think these dramas are overrated. 
Kill Me, Heal Me
A Gentleman's Dignity
Bitter Blood
City Hunter
Ghost
Queen In Hyun's Man
Reply 1997
White Christmas
You're All Surrounded
You're Beautiful
Ohhh and kill me heal me!! I mean seriously sooooo much fuss about that drama!
ok i agree about healer and city hunter. i think too that they are overrated an kind of boring but why so many people think that kill me heal me is overrated? i love this drama and of course you have your opinion but i was surprised! i also think that she was pretty was kind of boring in the last episodes. yong pal and mask also.. i only saw them for the actors and not for the stroy! and for the end Hyde, Jekyll, Me.. i expected more from this drama
Playful Kiss(i could neither complete anime nor drama)

Pinoccio(my brain agreed that it was a well-made drama but i just couldnt connect it any of the characters)