Is swearing at staff acceptable?

You might have gathered from previous posts that I work in a school.
Today a trainee member of staff was very upset as a pupil had sworn at her.
Are there truly any circumstances when this can be acceptable?
I would say NO!
I have looked on websites about Tourette's syndrome, and
90 percent of people with TS do not swear uncontrollably (coprolalia).
The above is a direct quote from a Tourette's webpage.
So even if the pupil claims to suffer from Tourette's swearing should not be acceptable. So, why do these pupils swear at staff, who are only trying to educate them?
There may be several explanations, the most obvious being they hear bad language used every day as part of normal speaking, and deem it acceptable.
This leads onto another post entirely ....that being...the acceptance? (or should I put more frequent usage of expletives is everyday language)
What was deemed unacceptable anywhere except the very worst part of society several years ago is gradually creeping into mainstream everyday usage.
Will we ever hear expletives, being used as if they are mainstream language, say on TV?
I seriously hope not.
I know the days when pupils would not dare to answer staff back are past, but why are they past? Is there anything at all that can be done?
I truly hope the trainee teacher who was on the receiving end of today's outburst is not disheartened by the incident, as I believe she is going to make an excellent teacher.