If you gonna lie, then lie to the old money grabbing, war organizing geezers! Now i know you wont ever meet that kind of people.
Now for the honest person on the block you should tell him: yes, our products are of quality (be a guinea pig to make sure they really are, in different case tell your manager that you doubt the product and want to sell something else - i am sure he will tell you to go F# your self so don't even ask him if you are not sure you can find another job in short time!).
When telling him that the product is of quality(and you are sure it is because you tested it on your skin), and you had examined opponent products describe the differences in ingredients, therapeutic reactions, price, quality (is it made from quality natural resources)...
Here is the chapter excerpt from Starbucks Experience book: McGraw-Hill Professional - Business
just started reading it, but on the skimming it has some great public relations ideas
All the best in your work!