This is an argument that plagues many people when starting an online business and those trying to keep one running.  The true answer to the question all depends on what you are promoting and how you go about promoting it.

You must realize when using click exchanges or as I call them “free traffic exchanges” is that the people are there for just that free traffic.  So, most people using exchanges are not interested at all in what you are offering they are just there for the traffic.  If you are going to be successful with click exchanges you should be offering a product that will help the user get even more traffic (preferably free). 

Click exchanges use timers usually about 10 – 15 seconds before the user is able to browse to another page. So, promote and promote fast is what you better do if using this online marketing method.  If you don’t get their attention in the first 2 - 4 seconds you can pretty much guarantee you won’t get a sale or email address.  Some adept exchange users browse multiple exchanges at the same time providing even less time for you to promote you product or service.

Think about what you are trying to promote test the exchanges and see how things work out.  Use a squeeze page w/audio so that even if they aren’t seeing your page they can at least hear (if they aren’t muted) the page.