Meh - IMO, appraisals aren't 'right' or 'wrong' any more, or less, than an AVM. An appraisal is an opinion, which is what drives the inconsistency between appraisers. AVM's are algorithms, and as such, they are - by definition - more consistent than appraisers. The other cool thing about AVM's is that they have the ability to return confidence intervals, which is something I wish appraisers were allowed to do.
The only way to determine the accuracy of an appraisal or AVM is to measure the results against subsequent sales of properties, and adjusting for market differences.
Just for grins - pull a Redfin property value for your place. My guess is that it's not too far off - maybe even closer than an appraiser might be. Pulled one for my place and it's within 3% of what I would have come up with.