Smoke it and find out.
I have had quite a few cigars that smelled like,well,ass or horse manure and smoked quite well,sweet even for the maduro ones.
Try and detect the type of smell,some putrid smells are good but some may be mold,wet,and raunchy damp smelling which indeed should be sent back or replaced.Dont smoke moldy smelling cigars,the inside could be where the mold lies and no sign on the outside at all.I usually light,taste,and decide.