Critical thinking skills vary.
I work at a public university that has gained quite a bit of local prestige. It also have a very liberal enterance policy--just about anybody who manages to finish high school can enter the university. But the university has very strick standards for students and we have a very high drop out rate. All of this adds up to a very mixed bag of first year students. Some come in with very big deficiencies in their educational background--a few others are down right brilliant. Some have no critical thinking skills at all and take and expect what the teacher says to be absolute truth. I'm not a very good speller myself, and often students do correct me--or I just ask them how you spell something so that they don't have to correct me

. But others are quiet tacken aback when the teachers says "I don't know."
Open ended questions can be a challenge--but a challenge they need.
They cheat and copy more than the typical North American student, and a Mexican would never refuse a friend who asked for help--that would be bad, but in my school it is fairly easy to establish test conditions under which cheating is very difficult. (we have bare bones rooms with plenty of space between the desks, students leave bags on a shelf by the door, we're in the bush so it's dead quiet most of the time, no hats allowed etc.
Most of my students know that learning English will be valuable to them, but not all of them are willing to put in the work it takes to learn a foreign langauge--some are waiting for the magic pill to come on to the market that will put us out of jobs....