I could imagine a world with a "allowed in the 99 only" list that would free the Otter to go into people's decks
Rending Volley already sees play in sideboards of Pioneer decks as an efficient answer to UW (blue/white) threats
Beyond this, there are other indicators of a fake card
The last Doctor card in the Blast from the Past set is The Eighth Doctor, a card that forces the player to mill three cards when it enters the battlefield, and then allows them to play a historic land or cast a historic permanent spell from their graveyard - whenever they use this ability, the chosen card is exiled when it leaves the battlefield
Often times an opponent will try to negate her effect with something like Breakthrough Skill and then roll over her with a large Special Summoned monster, but thanks to Dark Renewal, you can use her to remove another monster, and then revive her right back no longer negated
In addition to standard cards, there are also special rare cards known as holofoils or foils