Whoa! In case anyone missed it, *do not ever take a 1099 from a mystery shop company to a tax preparation shop.*
You are a Business Consultant, or Merchandiser, or an Auditor (you're paid to check pricing accuracy) but you are not a Mystery Shopper when you go do that tax return shop.
You go in with your Income as one figure, your "reimbursed expenses" as another figure, your other expenses are "office equipment" (your spy recorder and other tools of the trade, as well as computer, printer, scanner and anything else you use that is common office equipment) and "office supplies" (paper, toner). You bring in your vehicle expenses and mileage total -- do not show them the log of where you went!
Don't expect them to do your math for you. Add up each category yourself and bring them the total.
Do not be chatty with the guy. If he asks what you do, tell him "Business Consultant" and if he asks what that consists of be vague or lie through your teeth. The details have nothing to do with your tax return. "I help businesses set up displays" or "I do random price checks at Wal Mart so they don't get fined by the government". Don't say it's fun or exciting, yawn and say, "It's not very exciting but it helps pay the bills." If they want to get chatty and say, "How'd you get started doing that? My sister needs a job" say, "Sorry, I was lucky to find people who would pay me to do this and I'm not going to help you give me competition" and smile.
Be ready for this when you go it. Some people are just naturally nosy and naturally chatty. Cut them off at the pass but be nice about it. So rehearse your answers before you go in as far as what you might say if some Chatty Cathy wants to know all about your business.
And... there's another way to do this shop even if you don't qualify for it: Do the return without the Schedule C at all, then amend it to add it later. If you are close to break even on the Schedule C, it's not going to affect the bottom line much. So you could do a shop and leave off the Schedule C, then after they file it and the refund has processed, immediately amend it to add the Schedule C and either pay whatever extra tax it produces or get another refund. Just try to get the amendment in by April 15 so all the taxes are paid on time.
Time to build a bigger bridge.