One of many myths to dispel

 "Don't replace the carpet when you sell. The homebuyers will put in new carpet with their own colors anyway."

Reality: People buy with their emotions and justify with logic.
Homes that have ugly, worn out or smelly carpet don't get homebuyers excited as homes with the smell, feel, and look of brand new carpet. 
When buyers are NOT excited, they'll just move on to the next home.
Even people who want to put in their own colors. So iwhen your carpet is awful, you'll make money and sell faster if you put in new neutral carpet. Also splurge on the upgrade padding that will make the carpet feel more luxurious.