Leslie and Roxx wear portfolios of their own and each other's work, from which one can see their impressive skillset. They know how to match tattoo ink colors to natural skin colors and do more color work without outlining than I've ever seen in my own, admittedly limited, experience (where I live boasts maybe half a dozen tattoo artists). They also know how to put the tattoo in at exactly the right depth so that the lines stay crisp and neat year after year. Leslie's got some tattoos that I know are over ten years old, but the colors are bright and the fine lines still thin as a pencil drawing. These are skills they've developed over years of practice.
It's important to note, these two are very high end. Leslie and Roxx do custom work and are always booked up. Correspondence with them will often take a month, and their work is not cheap. They are both accomplished artists who design their own tattoos and will work with you to come up with the exact design and placement you want. They also do cover-ups and fixes for bad tattoos, so if you have a tattoo that's bled or faded or... you just wish you didn't have, consider asking them what they can do to make it gorgeous.
Besides that, the studio also boasts some very cute dogs.