I use Gas Buddy too, just be leery if you see a price on Gas Buddy a dime lower then every body else in the neighborhood it probably because some one is lying and probably is the gas station owner himself, even though he won't admit it.
Gas Buddy appears to be driven by the users reporting the price of each gas station. And like you said it’s likely getting gamed by gas station owners and can also suffer from outdated prices not being updated.
I’ve seen outdated prices per gallon using the app, but it’s good for letting me know the cheapest gas stations near me. Which is a help because the closest gas station near my home always has the highest prices.