As noted, you can get really cheap tubes that perform well, but, there is no way to know what you are getting from cheap no name brands. Kenko and Canon are both excellent, and I've owned both, but sold them after getting a cheap set aloong with a used camera that worked for me, They are branded Rokunar, are plastic, have a plastic camera mount, electrical contacts, and after 25 years, are still fine. I would not use them with a heavy lens, but with ordinary lenses like a 70-200mm f/4 or similar weight there is no issue. I've also used them with my 70-200mm f/2.8 and 100-400L, but only when the lens is supported by its tripod mount.
With this type of cheapie tubes, the joint between the tubes opens up under a heavy load, which then distorts the image. Mine have never taken any sort of a permanent set, and I knew what to look for, so I did not have any issues in use.
When using reversing rings, you need to be able to set the aperture of tthe lens in use. Some lenses can have a lever taped, or will stop down with just the aperture ring. Others, like the Canon FD are difficult to stop down unless mounted to a Canon body, or a adapter that will stop them down.