Yes and no.
On my hike in three Albergues, once in my room, twice in other rooms, people got bitten by bugs. I did not.
It is an issue.Maybe my blood was too sweet for them? I read something about silk liners or chemicals.
Hostels are all over the map in terms of cleanliness. I'd suggest to always inspect first, then make up your mind about staying. Quite a few stops were run by volunteers who had different priorities than yours or mine?