Age is Key: The biggest mistake is misjudging someone's age. Calling a 30-year-old man a `大叔` might imply he looks old. Calling a 70-year-old man a `大叔` might be awkward, as `大爷 (dàyé)` would be more appropriate. When in doubt, it's safer to use it for men who are clearly in the 40-60 age range.
`大叔 (dàshū)` vs. `叔叔 (shūshu)`: These are very similar. `叔叔` is generally used for one's actual father's younger brother. As a term of address for strangers, `叔叔` can feel slightly younger and more familiar than `大叔`. A child will almost always use `叔叔`. An adult might use `大叔` to show a bit more respectful distance.
`大叔 (dàshū)` vs. `大哥 (dàgē)`: `大哥` means “big brother” and is used for a man who is older than you, but closer to your own generation (e.g., 5-15 years older). Calling a 45-year-old man `大哥` can be a form of flattery, implying he looks younger than his age. Using `大叔` acknowledges a clear generational gap.
Not a “Sugar Daddy”: The attractive `大叔` trope should not be confused with the English concept of a “sugar daddy.” The `大叔`'s appeal is based on maturity, stability, and charm, not transactional relationships.