Owners should have some control over both by ensuring that each sales person has adequate time to spend with each customer and has the skills, knowledge, and ability to make that time a value to your customers. Clearly sales people must believe in your products. Additionally, however, the merchandising department has the responsibility to buy products in which the sales people have confidence and to maintain good relationships with vendors. We recommend that sales people meet with the sales manager for a minimum of forty minutes to an hour every month. We believe good working relationships are every individual's responsibility - Sales people must not fight openly amongst themselves.
Aggressive behavior brings down the entire organization.
I know of one sales manager who puts two feuding salespeople alone in a room and tells them to work out their differences. If, after 30 minutes, they can't convince him that they have solved the problem, one of them is sent home. It's amazing how fast they forget their petty differences and focus on getting along professionally. If sales people have a problem with someone in the company, they have a responsibility to work it out. If they can't work it out, they should involve the sales manager.