It is not recommended for these 2 type of businesses below to carry out SEM.
Unproven product demand: Traditional industries carry the advantage of having proven demand in their products/services. People have to be aware of the existence of your solution to be able to do a Google search for it. If your business is a disruptive technology, chances are search engine marketing is not suitable. For example, if you are Henry Ford trying to sell car at a time when people were still riding horses, consider social media marketing instead where you create a demand. On Google advertising, you must have existing demand for your products.
Unproven sales process: We always believe that marketing activities should enjoy a positive ROI and pay for itself. If you are investing money into advertising, it becomes extremely important to convert leads generated into customers. Search engine leads are typically qualified serious buyers. However, if you do not have a sales process yet that is proven to convert at good ratio, we highly recommend that you work on it first. That means a prompt follow-up system as well as enough salespeople to handle phonecalls.