Sales is and always has been a high turnover of staff. Were you hitting your targets?
Im in sales myself, and have seen PLENTY of "sales reps" come and go. The important thing to remember is there's a difference between the levels of sales reps out there. For example if you have a background from residential direct (and were good at it) you can walk onto a job in 90% of businesses, compare that to say where i worked last we had 2 people brought on to do my paperwork cause i was doing very well there and the time spent doing paperwork was basically down time for me, so 2 juniors were put on. They had aspirations of learing how to sell and joining the sales team. Well, they never had a chance! They were hired and advised of the possibility and to work hard etc. As soon as i left there they were gone. Since i left (my choice, not theirs) they've sacked2 of the other "sales reps" who were basically never hitting target. Its harsh out there for a person who tries sales and doesnt perform. Glad to hear you're not letting them shaft you
As long as you've got great references and a VERY strong sales orientation do what i did at my last place - walk in and take a very low retainer but negotiate for a high commission plan, never go for profit share, but always secure something along the lines of "overrack" ( eg, you sell a product for 1500 but the normal price is 1400, you should get some of the difference otherwise whats the point?). Then go nuts! as an example i had a 15k target of total sales (any of the companies products) to do in my first month, finished at 19k, second month moved to 20k target finished with 27k, third month moved to 25k finished with 29k, fourth month moved to 30k, finished at a touch under 40k. Then negotiate salary or even move into a different area, i took the second option and moved to development. Food for thought