Dairy products have a short shelf life, so they are willingly given discounts - sellers understand that if sour cream is not sold today, it will turn sour. But first you need to find out - the seller offers his product, or is he just a hired employee.
As for the meat, you need to look if the product is not leavened, how it smells and looks. At first, all this is difficult to determine, experience is needed, but you must always be observant, otherwise nothing will work. You can see how sellers handle meat, how carcasses are cut.
If they do this with you, then the meat is most likely fresh. But if you came to the market at the end of the working day, you need to focus only on smell, appearance and your experience.
When choosing a fish, you need to look at its shine. If you see that the seller constantly sprinkles fish with water, you should pass by. Fresh fish has a natural shine, it is covered with film and mucus.
Pay attention to the eyes, to the gills and be sure to sniff. If you don’t like the smell, refuse immediately. Look at the reaction of the seller: if he understands that you are versed in the product, he will offer you more recent products.
When buying fruits and vegetables, look at their appearance: there should be no spots, only an even color. Feel and check elasticity.
Sniff - smells won't let you down. When choosing berries, look at the bottom of the package - there should be no juice and mold.
In the choice of offal, also focus on your nose. For example, stomachs have a specific smell, but you need to understand the difference between a fresh and low-quality product. Understanding all this comes with experience.