Not sure about the canned good's thing. I don't think many vault residents would know how to cook; everything is done by a mister handy and provided by the vault.
But, things that could possible give away a vault dweller:
Accent; vaults would have probably developed thier own accents, especially vaults which are sealed for longer periods of time.
Language; vault dwellers would have a better handle on the complexities of language due to thier...
Education; vault dwellers would have probably recieved some formal education, giving them a better handle on the english language.
Paleness; kindof a no brainer. No sunlight=no tans=very different appearance from someone who's spent most of thier lives in the wasteland sun.
Footware; Along with the vault suite, a vault dweller would probably have some footware which could identify them. They'd probably be much better made than most of the footware in the wastes and so could be a quick visual indicator to someone who's looking for it.