There are also some Dramas tha were spoiled for me, but I also think that it´s not really a reason to stop watching or to don´t watch a Drama. Of course it´s annoying but if you really want to watch the Drama, go ahead although it was spoiled for you! About the comments there are sites like gooddrama.net where the People spoil, on MDL there isthat Spoiler button. I almost always read some comments about the Drama that I want to watch, if I read on gooddrama.nt or a site like that, then I just have to be careful, if it´s MDL then I avoid the Spoiler, coz there is this button to tell ATTENTION, SPOILER!
For me IRIS, Playful Kiss, Hana Kimi, Personal Taste, Coffee Prince and Secret Garden were spoiled, bt I watched them anyway coz they are great Dramas!