I listened to a podcast recently where a teacher made the claim that his job is to teach chemistry, not values, and I would argue that if this was really the case, he is failing at his job. If we think of values as being a set of cultural norms, then it is easy to argue that it is impossible to engage in the act of teaching without teaching values.
When we establish classroom rules, we are enforcing our own cultural norms over what is considered appropriate behaviour. For example, if you set the rule that only one person should talk at a time, you are enforcing your cultural norm about respect. If your students come to your classroom without this norm, and you are successful in your indoctrination, when they leave the classroom with the norm, you have taught them a value.
Even if you establish your classroom "rules" democratically, there is still an transfer of values that occurs. First, the value of democracy itself, that it is worthwhile to engage in conversation about things as important as rules, and the rules that are established will likely not reflect the values of an one individual, but rather a blend of the group.
School is filled with hidden values that we pass along to children, as John Taylor Gatto pointed out in his essay, "The Six Lesson School Teacher." Be on time, finish your work, respect each other’s personal space, don’t pick on people, be nice, and many more.
It is impossible to engage in the act of teaching, or even in any communication whatsoever, and not teach values. In every interaction between two or more people, there is an establishment of norms, sometimes explicitly, sometimes implicitly through body language and sometimes through exclusion of people not following your norm.
So when someone says they teach x and not values, I would challenge them and push them to see that this is impossible. We should at least be explicit with each other as educators what our cultural purpose is; the indoctrination of children to our society’s belief system.