Why does a fire always leave a weird smell in my house?

why does a fire always leave a weird smokey smell in my house? We got a chimney sweep about 3 months ago so that's definitely not the problem. Also, smoke was NOT coming in the house so that's also not the problem. both flues (top of chimney and bottom of chimney) were open so once again, that's not the problem. Would anyone know what the real, true problem is? Thank you!