I completed a single shop for Merc on 08/02/06 and never considered accepting another assignment for 2 reasons. The amount provided for the REQUIRED food items was $8 and change below the lowest on the menu; I've no interest in partial reimbursement shops. The primary reason though, was the difficulty I encountered with being paid.
At that time, Merc stated payment terms of net + 45; it took me until 11/10/06 to receive my money. During that period, I was told over the phone by 2 females and a male, all representing themselves as officers of the MSC, that my "check was in the mail." After it cleared my bank, I attempted to sever our relationship, but it hasn't been easy, as these folks don't seem to understand NO. In 2009, I received a letter from Merc requesting a reestablishment of our relationship and this year again began receiving shop notices, which only ceased when I strongly rebuked them for their difficulty in comprehending NO.
In the aforementioned letter of 2009, the chap stated as the reason I should consider assignments was that the MSC was under new management; I chose to pass, but he may well have been correct. As a matter of business, I don't forgive MSCs who tamper with my money.