i have to say that skip beat is manga and since manga isn´t still complete so drama didn´t had a proper ending too...but they probably even shouldnt start with that in first place when manga is still going on...
Who Are You? 2008 for some reason, I wanted more! I want to know what happened next? -The friends started dating? -The director, what happened to him? -What happened to brother?
Bad Guy. The drama was decent enough, then the ending hits you with a shoryuken. Effing bust.
Big was good (in my memory) but the ending was so confusing and terrible. I wanted to see more of Shin Wonho before he disappeared into Japan. :(
Hana Yori Dango - Never accepted the fact [spoiler]she ended up with Tsukasa instead of Rui.[/spoiler]
Monstar - Rushed and incomplete.
^ hot damn that's a big ass fail I WANTED TO SPOILER IT AND I CAN'T EVEN EDIT IT WOW
Glancing over my list, here are a few dramas that had endings I found unsatisfying: Innocent Man The Master's Sun* Rooftop Prince Aishiteiru to Ittekure* * not necessarily the ending, but the last 2 or so episodes were incredibly unsatisfying.
There are several I was unsatisfied with: Innocent Man - loved the drama to bits, wanted more in the ending. 49 days - Good but so friggin sad I couldn't stand it Big - no need to explain Two Weeks - so much left I want to know! Faith - one of my favs of all time, but really wanted to see at least a summary of what happened afterwards Why Why Love - ugh, not enough tissues to explain What happens in Bali - come on, really? It killed me, the whole thing did Lovers in Paris - Just left me with a big WTF moment Summer Fever - again, not enough tissues even if you knew it was coming Stairway to Heaven - Do I even need to explain? Bad, but Good: That Winter, the Wind Blows - because you don't know if it's Heaven or Earth, dammit! Sorry, I Love You - Done really well, but missing key plot endings... I could even forgive death if they completed it

There were a few endings that I really didn't like, but I am adding Moonshine and Valentine to the epic god awful endings plus the events leading to it :>

✔️ Fashion King.... Writer changed original  ending for fans and ruined it.... Don't know anyone who actually liked it

✔️ Lookout.... Killed one of my favorite characters and left t a few things unresolved

✔️ Gu family Book... Part of the ending could have been happy after they were parted for so long 


✔️ Scarlet Heart ryeo.... Why not have ending like Rooftop Prince or Splish Splash Love 

✔️ School 2017 (never kissed)