People hate salespeople. At the very least, their defenses are raised when they detect familiar patterns. They've likely had one or more negative experiences with salespeople. So when they detect familiar patterns and decide you're in sales, the conversation may already be over.
When you do a pattern analysis for all the bad salespeople you've run into, do you sound the same as them? If so, then why are you surprised when people treat you the same way you treat those bad salespeople?
If you want to be treated differently, you have to act differently. That's what a pattern interrupt is all about!