I have to agree with kura2ninja this has happened to me only with jdramas I don't remeber having this thought with any kdrama I have seen. These are some examples on the top of my head
Tumbling - with the synopsis and the picture I thought it was kind of stupid but I loved it! it's very heartfelt!
Kuzu no Honkai - the synopsis is over the top and sounds quite crazy but it's a very entertaining drama
Byakuyakou - this one sounds very crazy and messed up and it might be but you can not miss a second of each episode, the story really pulls you in.