Cheap bore scope

Are those cheap ($25-$50) endo/bore scopes sold on Amazon any good? It looks like angled mirror ends are attachable and they plug into a smartphone.
Opinions?

All the one's I've seen people post photo's from don't have enough magnification to really tell you much. Also, most look straight forward (fisheye) and don't have an angled attachment which makes it that much harder to see detail on the lands and grooves. I guess they're good enough to tell you if you're cleaning your bore good enough or not, but that's about it from what I've seen. Even the Lyman BoreCam leaves a lot to be desired, but it's much, much better than those cheap endoscopes.

Don't waste your money. The quality of the scope picture is so poor you can't see any detail.

They are OK for looking in the crankcase of a H.D. We saw what we needed to see. In that application I was surprised. I can see where the bore of a barrel would have a much different result.

I guess my question would be, are any bore scopes useful to those like me who have no experience with bore scopes?
Buying tools is the easy part.

The trick I use is to run a cleaning rod in from the muzzle end, with the camera looking in from the chamber/throat. The reflection off the brass jag lights up the bore very nicely, and as you slide the cleaning rod aft, towards the camera, the reflection will highlight the lands and grooves remarkably well.

Mine is a Snap-On BK5500. Cost about a hundred bucks used and has a color monitor.

I tried one of those cheapie ones that plugs into your camera or computer. Resolution was pretty bad, but it only cost $30. You get what you pay for. On the bright side, it was small enough to fit down a 223 barrel. The Snap on won't fit down a 30 cal barrel.

I got my Lyman for $167. Not sure if that was a low dip or still can get them.

You do have to be careful with it, the USB ports that they use for power and camera are delicate.

I thought it was well worth the cost.

As Mr. Furious noted its not perfect, but its awfully good. Having worked with and around metal a lot I can see all I need to.

Pictures are not great as the resolution is not hot, but overall I was impressed, my brother was and got one as well.

What was most interesting was to look at a range of barrels (XC/Shilen, McGowan, LW. Remington Original, various 1903, 1917 and K-31, Savage original and see what the finish looked like.

Hammer forged Remington was very smooth though not the best shooter (cleans up easily though)

I was able to confirm how much better the Carbon Killer 2000 was for cleaning barrels and how much cleaning was needed.

I've got a Lyman bore scope/cam, and I could see the pits/tool marks/etc on brand new (no shots fired) Savage barrels, it's a bit depressing to see that on a brand new barrel, but then savages are known for this. I also used it an Anschutz, big difference in bore quality, but in price as well. It's worth the $$ but just remember it's not a $750 bore scope either.

I bought a cheap one from Amazon and after shipping it was still less than $7. Hooked to a very old, slow laptop, the picture was kind of jumpy. Looked down a .45 barrel and could see it was clean. I'll also use it on engines. Going to try it on a faster computer and see if it is any better.