Cheap Aukey earbuds quality expectations?

I bought a pair of £10 aukey bluetooth earbuds from the mymemory deal a week ago. They have a steady constant background static that is very distracting, especially with quieter stuff.

Is this usual in cheap earbuds? I was assuming they might be a bit tinny but OK for watching tv and so forth. But being digital I thought they would be fairly clear otherwise? Thinking of trying to swap them, though they do claim to test all returns, whether I'm just expecting too much?
Thanks.