Directive advertising delivers returns albeit over a longer range time period. (60 to 120 days with repeat residuals.) Google AdWords is an example of directive advertising -- people are looking for what you have ...

On the other hand there is so called "creative" advertising -- this is more for branding and product awareness. You may get some sales but they will be few. However, it gets your name out there and builds branding (and credibility) for you.

So, ROMI (return on marketing investment) is generally below expectation short run but necessary for long term success.

The exception to the above is a properly made creative with a strong CTA (call to action) message. Special savings or some inducement to the consumer -- here you might have success generating sales.

Bottom line, the results are pivotal on your methods, placements, offer, and marketing budget. The answer is "how long is the string" or "42".