[T.G]

"Does that affect the product inside?"
It could, but it's unlikely unless someone is smoking an infused or flavored cigar. People at the factory smoke around the tobacco and finished cigars all the time.


"Is this something you should avoid without permission?"
Every B&M has their own policy, it's best to ask or look for a sign on the door that indicates if it's permitted or not.

The exception is flavored and infused, never walk in there with a lit one of those.
Even if it doesn't do anything, people will often freak out.