What makes a good ad?
The most successful ads are usually ones that have a clear concise title, a thorough and accurate description with good punctuation, clear pricing, excellent images and any other information which is relevant such as shipping costs etc.
When writing your ads it's important to try and put yourself in the position of the kind of person you're trying to attract, and ask yourself what you'd want to see if you were interested in buying, and write your ad accordingly.
Generally speaking, if there were two ads advertising the same item and one of them was clear and concise with lots of information and the other ad was basic with little information, the ad with more information will vastly outperform the basic one.
Ads with little information or bad punctuation send 'bad vibes' to buyers who will look elsewhere to buy.