I want to preface this by writing that I do keep my hands clean, my nails trimmed and cleaned, and I do like to make sure my hands are moisturized especially in the winter. That being said...
I don't get the spending money and time to make your nails look good thing. This goes for men and women. I know, I'm probably in the minority on this site and I'm happy to be. I guess I could see having a nail job done if you were a hand model or had straight-up nasty hands and were self-conscious about it. I guess I could see benefit if it helps you relax too.
In general, I think anything more than basic hand hygine (general cleanliness, moisturizing) is ridiculous. I know it runs the gammut. You've got people with fine looking hands wanting to make their mitts look "more attractive"...and then you've got people flaunting their two inch long leopard print painted nails that are pierced with gold and diamond bling hanging off of them thinking it's making them sexy. I think it's all ridiculous. Again, unless you have nasty hands, are a hand model, or equate it to some form of meditation I think it's silly. Just my opinion.
It's actually a turn off for me. I like a woman who's not afraid to get down and dirty and come caving, rock climbing, ect. with me. When I see someone with "well used" more natural looking hands, it tells me they've probably been grabbing life by the balls and enjoying it. I forgot, this thread's about guys getting manicures. Huh?! Anyway, I guess I'd try it once as I'll try anything once as long as it's not unhealthy, but I already know that I'm not vain enough to make it a repeat endeavor (since I'm not a hand model, don't have nasty hands, and practice other forms of meditation).
I'm not trying to offend anyone, so sorry if I do. This is just my opinion. To sum it up: Man, I could give and F about what your digits look like as long as they aren't crazy haggard.