One thing most people don't understand is how ubiquitous bacteria are. Simply put, they are everywhere!!! I promise you, that even if you take the best precautions, and sanitize everything, you will find bacteria in your beer.
The question is not whether or not there are bacteria in your beer, but how prolific they are. You could spend the money on a microscope, and you will see bacteria. Or you can simply accept that they are there, but work to minimize the amount that is in your beer.
Plus there is the additional work of actually preparing the slides (do you remember how to do gram stains?). You need a 1000x oil immersion scope. And you also need to know how to interpret what you see.
Personally, that sounds like way to much work and money for what is supposed to by a fun hobby. Now, if you are like me, and just love using a microscope to look at all the little things that the naked eye can't see, then it sounds like an excellent way to combine your two favorite things!
That's my two-cents.