There are so many.
1) The pay - You are paid way, way, way below the market rate. It's almost criminal.
2) The founders - The COO in particular is a nasty piece of work. A compulsive liar throughout my time there. Right from the interview up until the day I left he would lie about the things we discussed.
3 - The commission structure is absolutely ludicrous. Targets are completely untenable and it is heavily bias towards AM.
4 - Management - The management within the sales team was utterly inept. There was no strategy and absolutely no long-term planning.
5 - Uncomfortable - Encouraging, in some cases practically forcing, people to use their own private social networks to add prospective clients and aggressively pitch to them.
6 - Turnover of staff - I was there for 8 months and within that period the team more or less completely changed.