Stayman is a bid that asks a question, but does not show anything. A player cannot be damaged if he makes assumptions about what a player holds from the statement that he plays Stayman.
A player who when he bids 2C either has a four-card major or a weak hand with long clubs is playing Stayman. A player who always guarantees a four-card major when he bids 2C is playing Stayman. A player who has more complex rebids so when he bids Stayman may have a variety of types of hand, some with a four-card major, some without, is playing Stayman.
If a player wishes to know what hands a player who uses Stayman holds then it is easy for him to ask but he should not assume.
One of the sadnesses of this game is that there are so many different ways to play, but beginners do not get told this, so many of them get upset when they find things are not played their way in the real world.