I have had two very different careers in my life. I worked in restaurants, primarily as a chef for most of my life but I sold mattresses and appliances for ten years at The Hudson Bay Company and am currently back into that profession, hopefully for the rest of my working life.
Commission sales is very much like serving tables except that sales is a job you can retire from with benefits.
I have sold thousands of mattresses so I'll share a few tips on how to buy one.

Every company that sells mattresses sells essentially the same products and the same brands but they make it purposely difficult for you as a consumer to compare products. If you were buying a fridge you could just compare model numbers but not with mattresses. Companies will call their mattresses by different names and make them slightly different from their competition. If Company A sells "The Liberty" by Simmons, Company B will sell about the same product and call it something different, maybe "The Lakeview".

If you are looking to buy a new mattress and have a Facebook page just ask your friends what company they had a positive experience with or go to a place you had a positive experience with in the past.

Don't shop around and flop on every bed in town because you'll just get confused. A competent mattress salesperson is your tour guide. They know their floor and what's on it.
I personally prefer Simmons Beautyrest and have slept on one for 15 years so I tend to sell a lot of them because salespeople usually sell products that they own and believe in.

If you are looking for a new mattress for a guest room, consider taking the one out of your primary bedroom and putting it there and buying a new one for your primary room.

Some very important tips to buying a primary mattress for adults are:

Plan on spending an hour buying it and take your spouse with you if you have one.

Don't cheap out on your mattress!!! You're going to spend 6-8 hours on it every day! A good mattress is a great investment.

Firm DOES NOT mean good. Comfortable does mean good. Your choice is a personal choice so it's up to you to decide what is comfortable for you.

A mattress will ALWAYS be firmer when you sleep on it than it felt in the store. In the store you are on it for such a short period of time so your body doesn't really get the real feel of it. If you're wavering between two, choose the softer one. The most common reason for a comfort exchange is because it's too firm.

After you choose "THE ONE", ask the sales person if it will go on sale soon if it's not on sale.

A mattress will ALWAYS look bigger and higher when it gets delivered. The reasons are that in the showroom there is no linen on it, you are wearing your shoes and it's a huge room compared to your bedroom. A regular boxespring is 9" high but there is a "low profile box spring" that is 5". It will make your bed look shorter and will be easier to get in if you're shorter. There is also a "low profile frame" that goes from 7" to 5".

A queen boxspring can be bought as one piece or two. A split queen box is for tight corners, basement apartments or motor homes. You can't put your new mattress on an old boxspring. The old boxspring wears but you can't see it. Your warranty is void if your new mattress is not supported properly. READ YOUR WARRANTY!

If possible take delivery on the first day of your days off so you can laze around the first morning that you wake up in it!

If you have any questions I'll try to answer them. Sleep well!