I had a fairly negative experience at The Flying Pig hostel, which sadly was not alleviated by speaking with staff.
In my first room, I could see dead bed bugs within the bed frame (stuck there in cobwebs). I brought this up with staff, they went into the room, inspected it, didn't see anything, and had me point out exactly where it was and still didn't see anything; this was quite awkward, as there were many other people in the room. However they did move me to an alternate 8-bed room.
In the 8-bed room, I again found dead bed bugs, but this time in the bedsheets. At this point I accepted defeat and simply didn't say anything to the staff.
In both of the rooms that I was in, they were dimmly lit (contrary to how the rooms are shown in the images), the area around the matress were disgusting (it looks like the sides/under the matress have not been cleaned in months), and the floor was made of some bizarre fabric-type material which I can't imagine get cleaned very well.
At one point on my trip, I had left 500g sealed chocolate bars on my bed (planning to later place them into my suitcase). Hours later I had come back with a notice on my bed saying that the chocolate bars were moved to the kitchen. The chocolate bars were thankfully not stolen, but it was just so ridiculous to have sealed food items taken from my bed by the hostel staff.
There were more negative aspects of this hostel, but I've reached the character limit. This hostel is NOT cleanly.