Nothing, absolutely nothing, used to upset me more than a salesrep who would rush out of a sales call and refuse to take the time to debrief. "It went great, great job. Thanks! You were great..".
Aside from not really advancing the sales opportunity along - how does that kind of feedback help you to improve as a Sales Engineer? It doesn't! Even when reps would sit down with you to debrief it was often a haphazard affair without much structure for personal feedback. So after a while I came up with the T3-B3-N3 system. It's very, very simple. Try this:
"What were the Top 3 things I said or did that you really liked and I should do again? What were the Bottom 3 things I said or did that I should never do again? And what are the Next 3 things I should consider in a similar situation that I didn't do this time?"
Be prepared - you may not always like what you hear, but it is great feedback. Once you get this feedback you need to act upon it, and not let it fall upon deaf ears. You'll also find that about 25% of reps will reciprocate and ask you the same question in reverse.
So give it a try : T3-B3-N3!!