While the marketing methods are different for PPC as compared to SEO, many of the same principles apply. After all, this is still marketing in a competitive marketplace, and good markets are always competitive.
I have always thought that the idea of strictly looking for markets with low competition to be generally bad advice. What you want is high profitability with “relatively” low competition, as it relates to the profit potential. If you focus strictly on the low competition you generally find yourself in poor, very bad, or even no commercially viable markets.
If you are still at the stage of choosing a market niche then you should look closely at the competition, particularly for the keywords you plan to target. If you are looking at a low margin item and plan to compete against competitors that have much better margins than you, it will be tough to find profitable keywords. Likewise, if you choose a market that has competitors with high ticket items, that sell in volume, and you want to compete for the same keywords with lower volume item, or low priced items, you simply will not be garner the same ROI and will be pushed out of the marketplace for the best ad positions.
It is essential to consider your competition for PPC marketing, though you shouldn’t simply dismiss a niche because it is competitive. It is competitive for a reason, it means that many marketers have found a way to make a profit, and you can be sure to make a profit as well as long as you can devise a clever marketing strategy.