The staff I fire for being rude and incompetant usually end up at one of the area home depots.
Home depot has been losing massive market share for several years now yet there is still a very complacent message handed down to their store managers. They quite simply are not driven to perform and if the management team is not driven it filters down to the staff.
Personally I hire both retired age folks and student age folks and rarely in between unless they have a great skillset. The old folks love to talk and give good customer service and they have great knowledge (most come from related fields and this is a way for them to stay connected). The students can slug the product and can learn from the older staffers.
Both also fit nicely into a lower wage bracket which helps me keep costs down. Wages for big box stores are a huge expense, often coming in around 15% of gross sales yearly.