Here's an existing source of analysis of the quality of a lot of mostly very cheap products, some of which proved to be actually dangerous: https://www.youtube

Here's an existing source of analysis of the quality of a lot of mostly very cheap products, some of which proved to be actually dangerous: https://www.youtube.com/user/bigclivedotcom/videos https://www.youtube.com/user/bigclivedotcom/videos Watch enough of the videos and you'll start to see some common problems. Keeping the cost low is what usually results in poor construction quality. Failing to add protection for Li-Ion batteries. AC powered equipment that is dangerously wired. Poor design. Stupid design. Stuff that just could not possibly work in the first place (car ozone generators with just an LED in them and nothing else.) Stuff that emits toxins (over powered ozone generators). Stuff not designed to be repaired (glued together). And teardowns of equipment that is well designed and built also. Part of identifying common failures is identifying common successes as well so people know what to look for (good and bad) when buying stuff.