If you ask someone for a little favour, e.g. to close his door whenever he's listening to loud music or television, but this person keeps "forgetting" this, always. What is a term to describe this kind of person?
There are many words that can be used; that person could be forgetful, or that person could be discourteous. It depends on if you want emphasize the cause or the effect.
discourteous (adj.) showing rudeness and a lack of consideration for other people
absentminded (adj.) (of a person or a person's behavior or manner) having or showing a habitually forgetful or inattentive disposition
My thesaurus lists these promising synonyms for absentminded:
- distracted, preoccupied, inattentive
Maybe it's just me but I read the title and content of this question differently. I agree with @user3169 about "inconsiderate" as an answer to the content, but as for "someone who always forgets about his favours" a word that comes to mind is "ingrate". An ingrate is "an ungrateful person".
Depending on whether the person was forgetting through malice or absentmindedness, I'd describe them as either inconsiderate, or forgetful/absentminded.