In both professional and social settings, it's all in the details. We, the people who are judgemental and/or observant and quite vocal about what we see and think, pay attention to the smallest of details. At a certain French luxury boutique, I always looked at customers hands. If their hands were well groomed (for both men and women) - hands free of dirt, debris, and other unsightly flaws - and their nails were tended, I knew that these people would have a greater ability and chance to purchase. My thinking - if they spent a few extra moments and/or money to keep up their appearance, and cared enough to make this investment, they also cared enough to invest in a larger purchase and keep up their appearance as well with something from my exclusive store. Don't get me wrong - I wouldn't withhold assistance from potential customers if their hands and nails weren't up to my expectations - but it was a foolproof indicator, most of the time.
So, boys and girls, do yourself a favour. Make sure your hands and nails are properly tended. You need not spring for weekly manicures if unable - but you can quite easily invest in a small, durable nail brush. I keep one by the sink in my bathroom, as well as in the shower. Wash your hands with a mild soap, spending a few seconds to scrub the top of each nail, and underneath as well. A premium hand lotion or treatment is also a wise addition as well.
During college, I served on a leadership council for my university's president. One of my fellow student leaders, a very heterosexual "guys' guy" fraternity type - used to always (half jokingly, half seriously) comment on a professor of his, who apparently had very well groomed hands. My point is - having clean, presentable hands implies nothing about one's sexual preferences.
In a business setting - think of how often you use your hands. You may be promoting a new item which you hold in your hands. You may be shaking hands. You may be demonstrating a new product with your hands. You may present a business card.
Think about shaking someone's hand. When meeting someone for the first time, the very first contact you make is done by approaching the individual with your arm outstretched and your hand extended, ready to grasp their hand, solidly shake, and introduce yourself. Regardless of the task or situation - it's all about the details. You never know who's watching.