Curious Question

So where I live there are a lot of mattress retailers. Like a lot. You know how there are those images on the internet of two starbucks right across the street from each other? it’s literally like that. Anyways I have back pains at night and I have been going into these stores more browsing than anything cause I don’t know exactly what I am looking for however I expect to have a clearer idea when I leave than when I first entered.
The problem is unlike on this forum where there seems to be more legit knowledge and experience with choosing the best mattress, should I avoid purchasing one from these retailers and is there a better alternative?
Maybe a business that someone has used that sells mattresses for specific purpose (like backpain or whatever) that isn’t from one of the large manufacturers? I guess another way to interpret the question is can I trust what I am being told and sold on at these locations? I kinda wanna name names but not sure how appropriate that is but you get me. Thanks.
You can view more of my reason for concern here.