In the Gloomy Wood area of Alton Towers there is a brilliant dark ride called Duel: The Haunted House Strikes Back. It is quite an unappreciated ride because people usually walk past the "Shooty Uppy Ride" (as I've previously heard it be called) as a way to get over to Nemesis and Air only to go in this ride when there's nothing else to do or it's raining.
This interactive dark ride has an amazing queue line full of effects to give you an immersive experience of a haunted house. As soon as you enter the house you are hit with a brilliant smell that many might find horrible, I love it. It adds to the feeling of going through a haunted house. This smell is only used in a small area of the queue line (the very first time you enter the building) so just expect a queue as I stand there breathing heavily not letting anyone past as I soak in the smell.
A very similar smell is found in Hex when you enter the octagon room. However this slightly different version I don't like as much because it smell a lot stronger. The stronger Hex smell really does work well with the ride and the theming and the Duel smell works well. They both work well in their ride but I do prefer the Duel smell.