There's a bit of difference between consumer and industrial sales... And I appologies if I seem to be beating upon consumer salesmen and extolling industrial salesmen here; but I do that to get you to open your eyes and watch what they are up to.
As allergy victims, often tired during the sales pitch, we tend to be vulnerable to the feeling oriented sales pitch. ("But you want to feel better, don't you? And if this will make you feel better, then this is what you want, isn't it?" Hey! He said IF! "Now imagine yourself using this thing... and you feel better. This is what you want, isn't it?" Hey! He never said he could deliver! He asked you to IMAGINE he could deliver!)
I've been a consumer salesman while in college, (I appologise!) taken sales courses, and bought a lot of industrial stuff, both new and used.
If you want a good salesman, look for someone mature, an older fellow retired or laid off from industry, been in the community for a long time and knows the value of long term relationships. Contractors and store _owners_ often fall into this camp as well. Not Always!
What do consumer goods advertisments say? You will feel better, etc. The pitch often shows pictures designed to evoke feelings. The salesman is trying to get you to talk about subjective feelings that he can echo back to you along with the product.
Industrial goods are rated for highly specific and measurable things like particulate sizes and specific classes of chemicals. Things that can be measured. They don't much care about how you feel, or what you can imagine, they talk about specific effects.
Consumer goods are often oriented towards mild irritants like cigarrette smoke, pet dander, and pollen. Nothing life threatening. Often, the customer has no idea what is causing his or her problems, and neither does the manufacturer. Industrial goods are oriented towards specific toxics that can cause severe injury or death. And resultant legal liability. Specifics, not feelings!
A consumer salesman has nothing much to go on but the general claims of the manufacturer, deliberately vague to avoid liability problems. He sells the product or system once, often at a high commission. [Especially true in pharmacies!] Contrary to what he says, he won't likely see you again. The turnover rate amongst big ticket salesmen is very high; he may well have been selling water conditioners or lawn mowers the month before, and probably thinks he may be selling something else for someone else within the half year, like the folks I worked with. (And watch for traces of alcohol!)
An industrial salesman is trying to help a company meet specific goals and mandates for measurable concentrations. These are things the buying company often tests over and over. The salesman usually has lots of technical literature. Industry buys in quantity, often using the product on a continuing basis to enable them to produce something profitable; they want something that works, is reasonably cheap, and they want a long term relationship with the seller. If bad goods are sold, or supply is unavailable, the price of the goods may be trivial compared to the losses incurred while waiting for replacements.
The worst guys to talk to are the big ticket, high commission, one shot salesmen, like many of the second tier chain store appliance salesmen who derive most of their income from commissions, not salary. Same for the _non-owner_ used car salesmen. Unless you get an older fellow who has retired or been laid off from industry, (fairly common these days...) Watch Out! You are likely to be seen as meat on the hoof!
If I sound a bit abusive of consumer sales folks, it's because I have seen too many of them from both sides of the counter. I sold carpets and water softners in college. I could not stomach the lies I was told to tell in the softener business. I didn't tell the lies, and sold very little. (Though I was great at running the water tests in your kitchen sink!) Carpeting was a little better, simply because it was a subjective sale; but not that much better, as it was usualy a credit sale to a young couple who did not have enough credit, let alone cash! I proved that I was a terrible salesman there too.
I also took some sales courses, both product specific, and the Dale Carnegie Sales Course while selling cleaning supplies. (Amway. Again, I was not a very good salesman, but when demonstrated, most of the products sold themselves.) I've also acted as the customer in many sales training skits.
(And that says nothing of the outright lies and misinformation I have been told by young computer and appliance salesmen without a clue!)
There are good salesmen out there, don't misunderstand me. There are people who are genuinely (not just apparently) concerned and willing to help solve your problems. Many of them are former industrial people, either retired early, or laid off, and not use to the "you vs them" skulldugery of high comission sales. Look for the guy with the tendency to get either technical or specific about what the device does, rather than how good you will feel using it.
Of course, you can still buy a lemon from an industrial safety firm, but it will be an industrial strength lemon... You may pay a handling charge to return it, but they won't badger you into believing you are an idiot for returning it or buying it in the first place.
The down side is there may be minimunm quantities. But often, this will be a lower purchase price than the consumer goods. If not, keep looking. Industrial sales are generaly quite competetive as accountants like to shave pennies off the sale, and managers want reliable products and reliable delivery schedules.