HI sharmoot,
Welcome to the Mattress Forum! 
[quote]However on my way out I found BedMart just a couple blocks from them. I’ve found a couple quick mentions from Phoenix about them but I couldn’t find much detail on their quality.
The salesperson explained that it had a high density foam core and a Talalay latex layer on top, but she didn’t have any of the densities on hand. I thoroughly enjoyed the mattress,[/quote]
You are correct, there are no details about the product on their web site. As I think you’re already aware from your perusal on this site, I would always make sure that you find out information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase. You stated that the mattress has a polyfoam core, so you’d want to know the density and thickness of that core. Additionally, find out about the type/blend/ILD and thickness of the latex layer. In the photo on the web site, it appears that there is also polyfoam quilted to the ticking, so be sure to find out what else is contained within the mattress.
King Koil, like many large mattress companies, will employ different licensees (manufacturing facilities) to produce their products across the country. The label on the outside has nothing to do with the product on the inside, so unless you’re specifically concerned with the reputation of the ownership/workforce of a particular manufacturing facility, the brand name won’t be part of the meaningful information that you need to acquire. The source for the information you seek would be from the actual retailer, and since you’re phoning them again I would seek out a more informed salesperson who can completely answer your questions.
I’m glad you’re finding the information here usable. I’m not sure what you’ve read since you found the site but just in case you haven’t read it yet … the first place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well he will sleep), durability (how long he will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
Phoenix