Here are some of the things they most dislike:
Being intruded upon or spied upon (they punish this severely).
The sound of bells, especially church bells. (The one exception are those bells that they hang on their horses’ harnesses.)
The crowing of a cock.
Iron. Long ago, those fearful of meeting faeries would carry a piece of iron (or steel) with them, especially a cross or a horseshoe.
Rue, St. Johns wort and yarrow are said to be anti-faery herbs.
Disorder and untidiness. It used to be said that a housewife who did not keep a neat home would be pinched by the faeries in punishment.
Empty pails or those filled with dirty water.
Rudness, selfishness, lack of generosity, people who are moody or melancholy.
Lies or deceptions by humans. Even evil faeries do not lie, although they may seriously mislead or deceive.
Theft of faery possessions by humans. Though they think it perfectly acceptable to steal from people, they are furious if people steal from them. Similarly, they have no sense of humor if one of their tricks gets played back on them.
Nagging wives or husband/wife beaters.
Humans who boast of faery gifts they’ve received.
Humans who break taboos (known as geasas) imposed by faeries. Often a faery gift is given with a magickally imposed prohibition attached to it. If the taboo is broken, the gift or power is often taken away.