i.e using the word NIKE in your title when your selling ADIDAS. So when someone searches for anything with "NIKE" your listing will show in the Nike section, giving more exposure to your "ADIDAS" listing 2 categorys for the price of 1 basicaly.
I was hit for keyword spamming for using the term "like new" in my listing. Once I took that term out and replaced it with "gently worn" I could relist the item.