Adding high traffic keywords to the title of an eBay listing can increase views in the search engine which in turn affects visits to the listing and the number of opportunities to produce a sale.
Choosing keywords which attract a specific audience who is likely to purchase results in better quality traffic. Improving the quality of the traffic to a listing can increase the chance of a sale.
Seek a balance between keywords which attract lots of shoppers, and keywords which attract the right shoppers. Sales conversion is a factor in eBay search ranking, therefore keywords which attract a large volume of low-quality traffic can negatively impact search ranking.
If you had an iPhone 6s gold you would want to include how man GB the phone has.
You wouldn't want to include the word "telephone" in the listing title. Chances are, people who are searching for an iPhone probably won't use the word telephone in their search, so it attracts the wrong kind of customer.