I was going to write a review but since this thread is on topic I'll write it here.
I've been asking the same question and have tried to understand whether this is just another neat toy or does it truly possess added value. I've done some reading and listening to those who own and use them. Some of these units range from expensive to very expensive but I decided to make the investment.
I bought a Wolfgang Foamaster Foam Gun. Because this is for personal or non-commercial use I selected the quart size.
The quality and craftsmanship of the unit is very good. Critical components and mixing valve are made from solid brass. All other components are a high grade plastic ensuring years of trouble free use and satisfaction.
For the most part the unit comes pre-assembeled and its operation is simple and straight forward. Car wash mixing ratios are clearly defined on the plastic cup and the spray nozzle rotates making it easy to reach those hard to get to places.
After mixing the solution according to the directions I hooked it up to the hose and got to work. The foam gun operated flawlessly laying down a sudsy layer of foam that covered the car but was also runny. Keep in mind that this was not a Foam Canon that works with a pressure washer.
The unit operated exactly as designed and its performance was predictable. At no time did it malfunction or under perform.
With the foamy solution applied and watching it run and drip a question that begged to be asked was; what is all the hoopla associated with these units?
There have been many discussions regarding what's best when washing a car; lots of suds or little suds. Mike Phillips shares my opinion and has a video here and the conclusion is; little or low suds.
I always hose down the car prior to washing. This loosens the dust and debris and begins to dissolve water soluble contaminates. Once complete I begin my wash regiment using the two bucket system.
Conclusion:
Do Foam Guns apply additional lubrication to loosen and float dirt and debris? Yes, but so does properly prepared washing solution, it's been doing it for a very long time. Keep in mind you still need to wash the car like you always have however now you've added an extra step.
Are these units somewhat "gimmicky"? In my opinion yes, but again my opinion is something I'm an expert on.
Toy - Yes
Value Added - No
