Gudanov:
You are in a K-Mart if the interior of the store looks at least twenty years old and there's a sight yellow-ish atmosphere from the combination of florescent lighting and age.
You are in a Wal-Mart if the store has a thin blue veneer that looks modern and cheap at the same time, as if you applied a Facebook(tm)-like template over the store. They are also marked by dystopian-style LCD screens playing advertisements everywhere you go.
You are in a Target if you so assaulted by red that you can make no actual judgement of the interior of the store. Another giveaway is if they shit you want instead of just shit you need.