If a sales person knows they will be removed for low returns, they may resort to getting sales at any price by promising things that cannot actually be delivered and 'bigging up' the ability of the company/product.
In the sales world, at least in the industrial sales world in which I found myself (trained engineer), budgets are agreed at the start of the year. These budgets will include obviously, sales and
profitability targets. It is easy to end up with a full order book, the trick is to do so achieving the required (and agreed) levels of return.
Having said that, sometimes it is in a company's interest to take low profit work for the contribution to the overhead, it is called marginal costing. However any sales person who embarks on this course without the active encouragement of their line manager (and higher) is sure to be invited to a meeting without coffee in very short order. They would not last long in any company even if they thought they had circumvented the inevitable.