I think if the company gives some notice that they're going to do this it might be tolerable but in general it would seem like a huge disincentive to work there

I think if the company gives some notice that they're going to do this it might be tolerable but in general it would seem like a huge disincentive to work there. If the employer can't be straightforward with you at the very beginning of your relationship, it's hard to imagine the situation improving with time.