Why does everything taste like Freetown supermarket?

I have been in Sierra Leone for over three months now. The rains have come and stayed - yes I know it is sunny most of the time but it still rains at least once a day (mostly at night). It is the middle of November and still the rains are heavy with hurricane type winds that force me to shut the windows which I truly hate, even more than the mosquitoes. Last night I shut the windows only for the winds to open a few of my not so good windows and my dining room got soaked, good and proper!
Speaking of dining rooms. I have notice a phenomenon here in Freetown. By the way I say Freetown simply because I haven't used any supermarkets outside the city. In the past few months I have been trying to recreate meals I have in the UK - spaghetti bolognaise, fish pie, pizza, stir fry with noodles etc. This has meant that I MUST shop at one of the many supermarkets in the west of Freetown - Select, Monoprix, Atsons (why did I even go in there?), Essential, Freetown, St Mary's and so on. Everytime I buy flour or pasta or biscuits or bread from any of you these supermarkets, these products taste of the supermarket I bought it from. I can't explain it to you but if you live in Freetown and shop in any of these stores you know what I mean. Is it that these things take so long on the shelves that they have absorbed the smell of the place? But then that means that the packaging itself is poor. Is it the heat? All of these places are air conditioned. What is it? Somebody scientific please explain.
By the way Freetown Supermarket, we know that you erased the best before date off the big Thousand Island dressing bottles. I do hope no one buys them!!!