Usually the natural instinct to see if you are getting a good deal on a product or to see if you can possibly get the item for cheaper one would only compare the original labeled price to the marked sale price.
Another good thing to keep in mind though is to keep an eye out for the last digit of the sale prices as many times retailers use this as a way to identify products that are on say clearance which should give you a better idea if it could get cheaper or not. From my personal experience, most retailers that end its price tag with a â€œ7â€ it usually means the product is on clearance. For example, $19.97, $4.97, 808.97 and so fourth.
Nowadays whenever I see items tagged like that it tends to make me gander more on whether or not I should get it, assuming I needed it, as oppose to looking at those how much you save signs.