An example of a room that has multiple Troll Stars (in the boxes) and no way of knowing which is the real one besides many random guesses.

A troll star is a star that can be obtained, but, won't raise your star counter. A troll star's appearance is identical to a normal stars appearance depending on the game they are in. They are usually indicators of where a nearby star is, even though Mario will have to trek back to this position to explore. The hidden star is usually in a very obscure spot, so the star may actually be helpful in that sense. Troll stars can found in several hacks. In later hacks, troll stars usually have a giveaway that they are fakes. Some are upside down, lopsided, or even have slight differences in appearance. However, there are always some stars that do nothing helpful at all. In most of the hacks listed below, there is a star which you have to randomly pick which star, in a room full of troll stars, the one real star. Troll stars can be found in these hacks:
Star Revenge
Hack Original Star Revenge / Redone · Star Revenge 2: To The Moon · Star Revenge 2: Night of Doom · Star Revenge 3: Mario on an Saoire · Star Revenge 4: The Kedama Takeover 64 · Star Revenge 0.5 - Unused Levels · Star Revenge 6: Luigi's Adventure · Star Revenge 7: Park of Time · Star Revenge 8: Scepter of Hope
Remake Star Revenge Redone Version 2 · Star Revenge 2.5: Remnant of Doom · Star Revenge 4: The Kedama Takeover Rewritten · Star Revenge 5: Neo Blue Realm · Star Revenge 6.5: Wrath of the Dim. Flower · Star Revenge 6.9: Luigi Lost in Time · Star Revenge 7.5: Kedowser's Return
Other Troll Star