Actually, it's good for you. When we were in college, our teacher told us that people just out of school like us were willing to do sales for a while if they wanted to understand people and society. No matter what your grades are, you can at least exercise your eloquence, toughness, perseverance and so on. I did do it for a while, and I felt very rewarding. So I encourage you to do it here. Even if you don't succeed, you can exercise yourself and accumulate some life experience, so you don't have to be a salesman in the future.