First you are correct, leveling your Pokémon up to level 50 is a good way to check DVs. There are other ways, but, this one is possibly the easiest to explain.
Now, when you are doing the rare-candy-to-level-50 trick it is imperative (important) that the Pokémon did not win any battles. Otherwise, your results may become flawed.
To check DVs effectively and efficently, I suggest you download The Individual Finder Finder from Meowth346's website. Just follow the program's instructions and everything should be fine.