a GOOD thing. Hey you're the good guys, and they are the good guys too!
Let's face it, they have a job to do, coming up with a fair market value, and no one is getting a mortgage without an appraisal! So, let's make their job as easy as possible. Here are a few suggestions:
1) In all likelihood you as the Realtor are the contact for the appraiser to gain access to the property. Make yourself available, and make contact with the appraiser as quickly as possible. (The lender should provide the appraiser with contact info for the Realtor). The faster the appraiser can get into the property the faster the appraisal can get done. No appraisal, no approval, no mortgage.
2) Meet the appraiser at the property. Assist the appraiser with introduction to the homeowner and access to the property.
3) By all means provide the appraiser with the best comps available!!! They will verify them and check for others anyway, but this is a great assist, and the worst that can happen is the appraiser says no thanks.
Saving the appraiser time and effort will speed your transaction and at the very least create a good working relationship with a needed and respected real estate professional.