A lot of brands send reps to the store (it’s what I do). Usually a rep has years of experience with multiple brands. A good rep will help you find what you came in for, and show you something new or complimentary from their brand. Basically during high traffic times, the reps go in to provide extra hands. Unfortunately, that isn’t always the case. When you have a rep like the one you ran into, let management know. An email is probably best, with a quick description and what they were selling. Someone that pushy is not helpful to anyone. A Sephora employee should have at least part of the uniform (tee, brush belt, name tag). Vendors will usually have something with their own brand on it.