Why is better to use SEM versus SEO sometimes:
– With SEM you can find instantly if your business is good or not. With SEO you need to wait weeks/months.
– Sometimes, SEM have higher guarantees to show your ad higher then SEO
– With SEM you don’t need to waste money on building pages, getting link exchanges, optimization. Also, with crappy pages, but ok from usability point of view, you can generate higher sales versus with perfect SEO optimized pages