The short answer is yes, there is nothing wrong with using stock photos in your marketing. BUT, it's not that simple.
My very first job was mowing grass. I had a half-dozen clients in my neighborhood and I started mowing their lawns when I was about 11 or 12. I even had an employee for a short time. I paid for many tanks of gas, loads of casette tapes (Google it) and even a few trips to the beach with money from mowing lawns.
My first real jobs where I had a boss and got a pay check was as a busboy at County Line Barbecue (on the lake) and Comet Cleaners (on Far West Blvd) both in Austin, Texas.