There is a constant debate as to if SEO is better than PPC and vice versa. Ultimately, the answer will 
always be ‘it depends’ since it depends on many factors that need to be understood and ‘tailor-fitted’ to your needs and objectives. For some people, SEO will work better than PPC. For others, it may not.
My general marketing strategy, when I implement one, tends to be one that better suits SEO rather than PPC. For this reason, I have a tendency to want to use SEO more than PPC, although the combination of both has also worked very well in the past for me too. As much as SEO is great for gaining traffic, there are some times when it is a bad idea to go down the SEO route for gaining traffic. Here are some examples of when it is bad to use SEO.
#1 Short Term (< 6 months)
Search engine optimization is most effective as a long term strategy – it takes Google and other search engines a while to process and crawl through your new website and its articles. How long it actually take Google and other search engines to do this is a question such as ‘how long is a piece of string?’ though since it depends on a lot of factors.
I have started several websites now and tend to find that it takes, at least, 6 months for the traffic to come in after publishing the first SEO-ready article. Therefore, if you are looking to gain traffic within 6 months, then SEO might not be your best bet to go for.
#2 General Targeting
SEO, just like PPC, relies on contextual targeting. Only the most relevant articles will appear on organic search results. Therefore, if you are looking to gain traffic for general and vague keywords, you should not be surprised that you will get little to no traffic at all.
It is best to use PPC when you have an extremely specific topic or niche to target, since this is where it is easier to gain high rankings for search phrases.
This can also apply to PPC, where you will find that general keyword targeting will result in a high CPC and irrelevant traffic clicking onto your advert, reducing the effective return on investment (ROI) your campaign has as a whole.
#3 Lack of Time
SEO will take a lot more time to implement than a PPC campaign. This is because there will be the unavoidable time in creating articles and doing other activities to further improve the SEO of the website. From this, if you are looking to gain traffic without having to dedicate a lot of time to the traffic generation, it probably won’t help you if you go for SEO.
