Cai, I have to say that having a supportive store can make or break a WMI. I have heard horror stores about managers that were A$$es and so on. So the store you are at does play a factor into it.
I can't speak for everyone, but for me, I spend less than $3 hours at the store so unless the class involves making a cake or icing, then I'm getting paid a little over $11 an hour or $33.50 a night. For me, it is right over my day job pay, so I'm totally happy with a part time job that pays well over min wage. If I have a bigger group, 7-9 students, then I'm looking at $43.50 a night, which is $14.50 a hour for three hours. After 10 the pay goes up $3 for every additional student a night.
It is not a job that will make you rich, unless you taught classes several times a day many days of the week. But it is a nice job to give you spending money. My day job pays the bills. My teaching is my extra money.
There are some expenses as a WMI, such as the cake and icing, but there are chances to earn gift certificates to use for Wilton products, will does send out Freebies now and then, and then depending on which store you teach at maybe a employee discount.
I've only had a few students in my 6 years that made me want to quit, but I just went home, vented and came back the next week ready to do it again. More often than not I get students that I miss when the go through the classes.
Cia, as far as the sucking the icing from the bag, that is #2 on my rule list that they get the first night of the first course. I do not allow them to lick their fingers or any of their decorating tools. I've had it happen a very few times, even now with the fingers they will stop with their fingers half way to their mouth and look in my direction to see if I saw them.