Funny enough whenever I see a tattoo on a westerner's body, not only is it usually wrong in the grammar/spelling sense. But it is ugly as hell. Would you let a 5 year old tattoo the word, "Strength" onto your body? That's akin to what I see when I see the typography/style of the tattoo. "Sir, not only does it not say Superman, the characters are backwards and missing strokes"

Any Chinese person who tells you the truth about what your tattoo says is being very kind to you, but most Chinese won't say anything bad since they have no reason to embarrass the person.

One time when I was still in college my family took a trip out to Mexico. I forgot what store we went into but the cashier asked my dad to write down the cashier's name (sorry forgot that too) into Chinese. My dad spent a decent amount of time to think of the proper characters, wrote it down and we were on our way. I still think about that incident a lot, like what if my dad was a jerk and wrote something stupid for this guy to get tattooed (he wouldn't). but even then he's essentially trusting my dad is not messing up his name in Chinese (it definitely wasn't something like Mark).