Most teachers think parents are not involved enough with their children's education and expect too much of schools, a survey says.
Teachers say they need more support from outside school
Reader's Digest found 92% wanted to tell parents their offspring had to do more work to achieve decent results.
Meanwhile, 80% would like to be able to refuse outright to teach the most disruptive pupils.
Many of the 572 staff interviewed complained that parents' poor behaviour had a knock-on effect in the classroom.
'Get your children to wash, please'
Three out of four said they resented spending time ensuring homework was completed, claiming it was families' responsibility.
English teacher Anna Mills, from Worthing, West Sussex, told researchers: "When I started teaching I used to ask pupils to read the next chapter for homework so we could discuss it at the next lesson.
"Now that's impossible because I can't assume they'll do it."
Some 83% of teachers said they would like to tell parents: "You're not realistic about your child's abilities."
Meanwhile, 77% wanted to say: "Please get your child to wash before school."
Daniela Thacker, a secondary school teacher from Birmingham, said: "My kids smell so bad it's tough to teach them. It's difficult to make them understand simple standards.
"At the start of each lesson I have to open all the windows and spray the room with air freshener to make teaching bearable."
A National Union of Teachers spokeswoman said: "Support from parents is fundamental to young people achieving at school.
"Crucial to every child's education is good behaviour and good discipline.
The poor behaviour of one child undermines the education of every other
child in the class."