I used to sell perfume wholesale at one point in my life and it's not just about scents or no scents sometimes, or about allergies, but also about particular types of scents. Sometimes it's about being allergic and sometimes it's about a negative association with certain types of scents. Asking guys if they like scents and if there's anything in particular that puts them off is a good idea. You'd be surprised how many men have negative associations with certain types of scents because of mom or ex-girlfriends or whatever. Many men have who have nothing against perfume still hate certain types of scents, so asking if they especially like things that are clean, musky, floral, fruity, spicy, powdery or whatever may actually increase the "growlf!" factor.