I forgot to also add some information about "selling" you stuff. Generally, sales reps from companies or rep groups "sell stuff" usually at the dealer and distributer level. It is why when people sometime talk to these folks they can have a bad experience as they are in the large quantity sales job and not working at a retail level with individual buyers.
Some companies employ Pro Staff, and some Rep groups have Technical Services people. These folks are usually contract employees and are often not actual employees. They are usually hired because they have a level of technical expertise with a type of product as established end users or technical expertise. They don't get these jobs because they are great sales people, and sales is not really what they do. They are more educators and subject matter experts who do training and help to explain how products work and the positives and negatives. Many of us are fairly agnostic as far as a particular love of the companies themselves and tend to be more shooter geeks. Most could go to work for their "competitors" as well. As an example, I have been shooting ACOGs longer than any other optic and it is still my favorite mid-range optic. I have been using them since they came out, and mine's serial number was in the 600 range as an indicator that I was a very early adopter. I have had Trijicon's "Sales reps" send people to my booth to explain how the reticules work when they didn't have their rep groups technical services guys available. I helped their customers and respected their rep because he was getting some questions above his knowledge level and rather than b.s. the end users he sent them to somebody who knew the product better than he did. Reps are sales guys, they move around in the industry, and are not always technical geeks about their products (especially with a big product line). Many have never used the product they are selling. That is why some companies retain folks who have actually used their products and understand the nuances from and end user point of view. Most of these people are, or have been, instructors and understand how to talk to people about how things work and how to use them.
I also do employee training for some dealers. This is so consumers can get good information from the other side of the counter at the gun shop. This is actually some of the most rewarding stuff I do because it multiplies quickly in helping to get solid information out to consumers. How many of the posters and readers of this thread would have preferred to have gotten some of this information from the guy behind the counter at the shop or from the person on the other end of the phone when you were buying a sight? It is what is very lost in this industry today.