This was the place that the booked for us to stay in Seoul Youth Hostel. We booked the whole dorm room because we had 6 person and accommodation in Seoul is very expensive.
The dorm room was clean, white bed sheets, but with only one toilet, we took turn using it. However, they have common bathrooms outside too and a common area with TV and drinking water.
This two nights was alright. Nevertheless, the last night it was noisy as they had school children staying next door for their school holidays. These children just ran and shouted without supervision and without any supervision from the adults. For what we paid for, I think we just had to bear with it. Don't worry our friend told us that there were other rooms that we could choose from for 2 persons (Maybe you can look for those, if you need better privacy)
This is how the dorm room looks like.
Cons: Could get a little noisy.