There 2 things to be aware of when it comes to 'dumb' adapters:
1 - nearly all of them will have been manufactured with an extra millimetre so that when you set your lens at infinity, the lens actually focuses slightly past it, you will need to focus back slightly. I guess this is so that they set some form of machining tolerance. Whilst to me this is not annoying, to some it is as they want to turn the focus ring to its end to reach infinity and want it to be focus.
2 - some photography snobs swear that more expensive adapters are manufactured with more precision in turns of the exact distance all the way around the adapter so the image via you lens is not affected on one side. Personally, ALL my dumb adapters are either Pixco or some cheap Chinese brand and I have not experienced this issue at all.