It is obvious you need to be buying from someone else.
It is obvious that degreasers are not the best soaps for washing trucks as you have found out the hard way.
There is a lot of garbage out there that you have to wade through to get to the good stuff most of the time.
I usually tell the vendors to send me a 5 gallon pail sample (I will pay for shipping) and if the product is good I will buy it and they have a new customer, if they hesitate or start rambling off every excuse known to man why they cannot do this, that should be an indicator that they don't have confidence in their product and I would not waste anymore time with them.
A pint, quart or gallon sample is not enough to fill my chemical hoses let alone wash some equipment to see how a product works so when they offer small samples like that, they have never been out in the field washing so they have no clue of what goes on, how much soap is needed to wash equipment and they probably have an inferior product most of the time.
I really hate it when chemical salesmen call me and waste my time because they have never washed anything but they know that their product is a great product and then the river of B.S. starts flooding when they start talking about ratios and how far it will go when washing trucks. I have heard that line of B.S. from so many salespeople and a few vendors that I stop them right there and tell them that they are full of it (Bull Shi*!) as they have no clue of what works out there and they have no clue of real ratios, they probably made up the ratios in their heads since they have never washed anything so they can tell you exactly where you need to be for the product to work.
Sounds like the company you buy from is in this category above and honestly, his degreasers are probably inferior also when put up against something that works, even out in the oil field there are better degreasers that probably don't cost as much and are better than what your guy sells. You have to quit listening to these salesmen and talk to other people out there, one guy in your area is not necessarily the "expert" that people think he is, want him to be or wishes he was, he is just a guy in your area that sells chemicals just like you could if you bought formulas and started packaging them or re-selling them and now BOOM! now you are a chemical guru also like he is. This is what happens all around the country a lot of times.
Don't get me wrong, there are some great vendors and some of them post on the bbs's because not all chemical salesmen are bad, most are though and have worthless, watered-down crap that just does not work, especially those that sell the "all in one cleaners" that claim to clean just about everything but in reality don't really clean anything at all and the only thing it is good for is aggravating you and wasting your time until you find a drain to dump it down and be done with it (got some of those also in the past but will not waste my time with them again).
Good luck.