Supermarket flier question
I read that manufacturers pay the supermarkets to put in ads for their products in the supermarket fliers and that they are not always on sale. A recent flier gave the original and sale price, then some products said "card price" and others had only a price with no mention of a sale.
How can you tell which products are really on sale when reading the fliers? Is there a site I could go to that could help me figure this out.
I really want to save money and have decided to start doing it at the supermarket.