Commissario
Aye you can't always, but there are times when it's exceptionally clear that someone either is, or was.
And the more of these symbols they have (and the bigger they are) the more sure you can be about what they are, especially when the person is "western" and given how demonised those symbols are due to their association.
Basically unless you're really really stupid in the likes of Europe and America you don't get what could be seen as Nazi symbols by mistake, and many tattooists are likely to query that you're sure you want them (if not refuse to do them).
And the more of these symbols they have (and the bigger they are) the more sure you can be about what they are, especially when the person is "western" and given how demonised those symbols are due to their association.
Basically unless you're really really stupid in the likes of Europe and America you don't get what could be seen as Nazi symbols by mistake, and many tattooists are likely to query that you're sure you want them (if not refuse to do them).