Ultimately, it is, but the ad will not sell the item, you will. The ad will just put you in contact with buyers. The best way to get qualified buyers to contact you, is to include as much relevant information as possible, and include a good photograph. Be as complete as possible in your description of condition, age, and features. Don't use abbreviations.
Abbreviations are common in print classified ads because the seller is billed by the character.
These ads are free, and abbreviations may confuse some potential buyers. With For Sale ads, in most cases it is best to include the price, not doing so may waste your time with response from buyers who are looking for something well below your asking price. Most importantly, follow up quickly and thoroughly when someone contacts you for more information. Classified ads can bring in potential buyers, but you have to close the deal. Be prepared for the expected question, such as additional information on condition, price flexibility, shipping information, etc.