Sorry, is there an acceptable limit on dirty crud under screens now? That's a new one. What next... your monitor can have 5 human hairs, 1 piece of excrement, a blob of jam and 2 small insects... it must have more than this to be able to return.
You have a limited amount of time to do that. Note to self don't order one of these anytime soon from OCUK as it might be yours..
That's only going to happen if you buy a B-grade monitor. OcUK can't sell it again as new.
Having said that, I purchased my current monitor - 27" IIyama 2560x1440 - as a B-grade. Not a thing wrong with it.
They shouldn't sell it as new, whether they do or not is another matter entirely.
This is the great thing about the internet... public word of mouth can change a lot of things.