[darkr]

Cheap stud finders are usually not great. The good ones are radar-based using similar frequency bands to wifi, but they cost lots of $$

[amerkhalid]

I bought a thermal camera as a fun toy, it is great at finding studs especially for walls that face outside. Also you can see pipes easily when hot water is running through them.

But it was not cheap, cost about $300.

If you just want to just find studs, use magnetic stud finder. Cost about $10. Very easy to use and accurate.

[mrgoldenbrown]

Cheap stud finders are only accurate for some wall construction types. They do not work on my older style plaster and lathe walls, for example.

[srik]

It might be possible to rent those nicer expensive ones. I'd check with local hardware stores.

[deskr]

You beat me to it. I'd say "usually not great" is putting it too lightly.

They're awful and if you don't realize they're awful then you might make regretful decisions based on their slanderous output.

[somehnguy]

The key to using stud finders is never trusting them and using multiple methods as a sanity check. For example, if it says a stud is as position x I'll sanity check by checking x-16" and x+16" because there should also be studs there. If nothing, maybe I'll try x-15, x-14, etc with the key being looking for some repeating pattern. Test moving vertically as well.

Combine with some knocking to feel/listen for a stud right against the wall vs an erroneously detected pipe 1/4" away.

I'll also use a neodymium magnet in certain situations to look for drywall nails/screws in conjunction with the other methods.

I don't fully trust any of these methods, but together they'll get you as confident as you can be short of having a couple hundred dollar detector or taking the wall apart.

[lancesells]

If it's drywall you can use use a cheap stud finder or just yours ears and hands to find studs fairly easy. Plaster might be a little harder but still doable. Also, look for outlets as those are attached to studs. Depending on the age and construction of the house studs will be 16 inches apart.

[sleepybrett]

...and can be rented.