They'll compare websites and the information provided on them to see who they're most comfortable doing business with. They'll get their first impression of your business from your website and first impressions are lasting.
How does your site compare? Does it show what makes you different from your competitors and how these differences benefit the customer? Does it make you look professional? Does it build trust? Does it enhance your image?
Using professional photos of your key people and facilities goes a long way toward building trust and attracting those customers that you're best suited to serve. Done properly, they'll do much to enhance your image.
Your site and the images on them control how you're perceived by potential customers. You don't need the best website in the world, you just need one that's a little better than your competitors. One that conveys meaningful information and builds trust.
Fortunately, this is not difficult as many of your competitors probably use stock photos. Images that don't provide meaningful information and that make them look just like everybody else.