... And again, I am not seeing how shopping at a grow store, as a matter of convenience (or not) is taking precedence over good security practices. These things are not mutually exclusive. Such a mentality, it seems to me, fails to consider a couple of things. One is that grow stores and their local atmospheres differ about as much as styles and methods of growing do. The other thing is that if you, yourself, see these stores\products solely as a "one stop shop for all things growing pot" and go in their with that mentality- or god forbid you do get questioned by LEO, well in that case it is no wonder they might be suspicious.
FFOF bags and "MJ-specific" nutrients? If you can't come to terms with the fact that most of these products, really, are NOT marketed specifically to MJ growers, you are driving the nails into your own coffin.
Don't help re-enforce this stereotype, tho, because people definitely grow other things besides cannabis indoors and they definitely go to "hydro stores" for the supplies. Furthermore some supplies such as ballasts, other lighting equipment and bulbs, HO inline fans, carbon filters, durable square containers, fabric pots, plastic trays, rooting hormone and plugs for clones, etc. can only be found in my area at the grow shop. The grow shop carries some of same things the hardware store does, too, and at the grow shop some things are cheaper! Case in point more varieties and larger bags of Espoma granular plant foods.
I think the same common sense rules to buying supplies at a "grow shop" apply to home improvement stores and nurseries as well. Dress normal, act natural, pay cash where ever possible, make sure you're not being followed and for added peace of mind use somebody else's vehicle, or get a ride from someone and don't bring the supplies directly back to where you are growing. And one could, just the same, arouse suspicions by buying lots of certain supplies at a home improvement/nursery/garden center. Especially in the dead of winter.