The four expressions are used with the verb "to be" so, that "be prepared" to discover them.
“Estar de mala leche"
Nothing has to do with the milk that you have taken this morning at breakfast. In fact, has nothing to do with cow's milk, or with the vegetable milks that are so fashionable now, forget about any kind of milk, as you know it until now.
It is means being in a bad mood.
Therefore, when you hear someone say that this is bad, it is better to say goodbye to him or her and tell him or her that you prefer to see them tomorrow.
“Estar hecho polvo"
As in the previous expression, when someone tells you that they are "hechos polvo" it is not that they have been cleaning the dust of their student apartment in Barcelona, or anywhere else, but that they are really tired or disgusted by something.
Normally you can be "hecho polvo" because you had a few days of hard work or study and after that period, now you have no strength for anything else. It is also used for disappointments or disappointments in general with your environment that leave you wanting nothing and with a good displeasure.
“Estar de resaca"
This word, has no meaning other than having left the previous night and having drunk more than necessary, when you get up the next day, and you talk to someone in your students flat in Barcelona and they ask you the typical one, ¿ How are you? Your answer can not be other than "Estoy de resaca". The hangover is a physical state that causes you headache, discomfort and desire to drink water.
“ Estar desvelado"
Of all last expressions, perhaps this is the expression you least listen to, because it is not very common in students, except during exams or days of nervousness in which you cannot sleep well. Being "sleepless" means that you have gone to sleep and it has not been possible to sleep, or that you have woken up in the middle of the night and have not been able to get back to sleep again.
Did you know any of them? Tell us the truth!