Inconsistent work weeks. Often you won't know what days you will have off until Sunday. There are no weekends off. With office meetings set behind full work days, you're likely to have 10-12 hour work days.
The base pay is only available to those who make specific number of sales for the week. If you're expected to make 4 sales that week and you only make 3, then the following week you won't get paid unless you hit that magic number. It's a great way for the business to save some money when sales are low, but you will feel it before management.