Scotty Kilmer, mechanic for the last 49 years, shows how you can use an economy borescope to see and fix problems on your car that otherwise you could never see. One handy tool here
yes, some of the cheap ones are garbage, but now the prices of really good ones has gone down quite a bit. AND you can get ones that work on your cell phone or laptop for the price you paid that actually work quite well
Got a cheap one from Amazon UK, £17 I think, 2M camera, it's going right back, unusable piece of junk.