Souvenir collecting is sometimes considered a form of obsessive-compulsive behavior, particularly when it becomes excessive and impacts daily life.
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The value of a bottle can be significantly impacted by its color; rare colors like amethyst or aqua can command much higher prices than common clear or green bottles.
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Some key collectors, known as key enthusiasts or keyophiles, categorize their keys not only by type of lock but also by the maker's mark or unique design features on the key's bitting (the part that interacts with the lock).
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