Paying for appraisal with low confidence in appraiser?

[Matt Mainini]

My friend and landlord of 2 years is selling her property, so we agree to split the appraisal fee and go with a guy neither of us personally know.  I no longer live in the property, but I'm familiar with it and want to purchase from her, and she would like to do seller financing.  

The issue I have is the appraiser is "done" but has not sent the report until payment is received.  One of the reasons payment wasn't "received" was that the check was lost in the washing machine.  He has delayed multiple times (frustrating), he has called me by 3 different names (mental issues?) and he has misspelled BOTH of our names on the invoice (mental issues?).  

My confidence in his work is, as you might imagine, very low at this point.  Do I go through with payment and accept the report as is? Or do I explain to him that his behavior gives me reason to caution moving forward with payment?  I have not signed any agreements, however I verbally agreed with my friend/seller to pay for half.  I will pay for half to keep our relationship intact, so I might do it simply for that reason alone, but I feel like I may be throwing away hundreds of dollars before I even send the money.