They work. You can use pH paper if you want to.
I think most people rely on soil tests because for a nominal sum you get a complete nutrient profile, and recommended rates of application.
This^^^^^^
Mine reads .03 low compared to a soil test.So I adjust for it.Mine cost $28.00 about 10 years ago.Yes, I use one often and have compared them to soil tests. Now I do have a little more upscale one that the $10 dollar one at the hardware store though but all I use on it is the ph meter. I don't know if I trust the nitrogen scale on it.
one thing about the meters is you get a snapshot of that one spot. Its best to dig a pint of soil from 10 spots though the food plot and mix it in a 5gal bucket to get the average of the entire plot. Its not uncommon for the ph to vary with a little distance across the plot