Stinky things smell bad. If your gym uniform is particularly stinky after a game of volleyball, you should probably wash it.
You might describe the gorgonzola cheese your sister loves as stinky. She, on the other hand, may object to your favorite perfume, describing it as stinky. Besides bad odors, the informal adjective stinky can also describe generally bad or rotten things: "You did a stinky job of cleaning the kitchen after you baked all that bread. There's flour everywhere!"