Is he interested if he stares but never smiles?

There is this guy who lives near me and I see him quite often and when I do he always stares at me-he hardly ever turns away or if I catch him looking he'll immediately turn away then look back again but he never smiles at me. Why? Is he interested because he stares or is he not interested because he never smiles? Guys-do you ever do this with a girl you like?

P.S. We've never spoken to each other.
Is he interested if he stares but never smiles?
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