There are exceptions, but for the most part the staff in these music stores don't have any incentive to learn a lot about gear when they are just buying time until their next career. It generally doesn't pay well. Again there are exceptions, but the general trend is low pay and low incentive. Which is not a lot different from just about any other service industry unfortunately. Things is changin...
The best thing you can do to increase your value as a guitar player is learn to sing. But most guitarists don't want to hear that, so we mod instead...hoping it will compensate.