It absolutely depends on the individual and the movie in question. For example, just about anyone -- male or female -- can appreciate a great movie such as The Good, The Bad and The Ugly. Spaghetti or not, it's recognized as one of the greatest movies in film history, and it's hard not to appreciate the artistry involved. However, the deeper you delve into the genre, the lesser the overall quality of the films becomes, and I believe that's when Spaghettis start becoming a hardsell for the wives and girlfriends. The machismo and over-the-top violence -- not to mention the way women are generally treated in these movies -- is obviously tailored to male audiences.
Talking from experience here, my wife would gladly sit down and watch any of the Dollars films with me, because they are truly classic movies that just about anyone can enjoy. Same goes for other non-Spaghetti Eastwood films such as Unforgiven and Hang Em High. (Eastwood in general has a pretty decent female following I'd presume.) However, I don't think she'd sit through something like Django or Death Rides A Horse, these are films that in my opinion you would have to be a true fan of the genre to appreciate.