No matter how many hours availability you submit, you will only be assigned around 10 hours of teaching per week
They will blame you for the technical problems they have
They will hide students' feedback when you ask for it saying that it is usually negative
Teacher managers don't reply to your messages
You have No Student classes very often so you waste your time
Their English is horrible so it's always very hard to understand what they say in their emails
They will not miss an opportunity to penalise you and at the evaluation period (which is every 6 months) they will come up with excuses so they don't have to promote you to a higher Rank and increase your salary.
When you get fed up and decide to leave they will just hire someone new that's why they are always advertising that they are looking for teachers.