Sales engineers are a readily available resource of application knowledge. Unlike information pulled from the Internet, sales engineers possess real-time product information. They are also exposed to many different product applications and are a wealth of tacit knowledge. All readily available for sharing with their customers.
OEM design engineers often find themselves sailing in uncharted waters. In the application of electric heaters or feedthroughs for instance, designers don't always have a full grasp of heater or feedthrough design constraints. When these situations occur, the heater sales person provides a real benefit in teaching and advising the designer what is possible. Additionally, many sales engineers have access to unpublished product and application information, which can be hugely important when attempting to build a leading edge product.
Of course any solutions proposed are likely to be based upon the products sold by the representative, but the best sales people will share the virtues of their products openly and honestly. The best sales engineers will even admit when they lack the product or experience to solve the problem, but even in this situation, you can be sure their perspective will still be of value. The goal is to build a long-term, trusting relationship - one of value to both parties. Sales engineers are in the business of dealing with people and making the important connections between customers and manufacturers. They make it their business to know what’s going on with products, companies and industries.
As an engineer or purchasing professional responsible for the design and manufacture of OEM equipment, know that working closely with a vendor sales engineer will save you precious time and greatly improve the likelihood of successful project outcomes. Their success, and your success, go hand-in-hand.