All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
There is no specific indication by which a son knows whether or not he is dutiful and obedient to his parents, but if he treats them well, avoids mistreating them by any kind of mistreatment, provides them with any good that he may give to them, and obeys them in what is permissible, then he is considered as being dutiful and obedient to them.
The Fiqh Encyclopedia, when speaking about the meaning of dutifulness to parents in terminology, reads, “It mostly refers to kindness through gentle, lenient speech that indicates compassion and love, and avoiding harsh words that entail aversion; while coupling this with compassion, affection, and kindness either with money or other good deeds.”
The matter is as you mentioned, that obedience to parents is not absolute and has limits, which you outlined in your question. We have already clarified this in fatwa 277330. Therefore, not everything that angers the parents is considered disobedience; so it is not obligatory to obey them in regard to wearing a certain type of clothes, and the same applies to food, drink, and studying in a particular specialty; unless they have a correct purpose for that.
Nevertheless, the son should try to please them, and whenever it is possible for him to obey them and avoid their anger, he should do so.
Allah knows best.