Pitfalls for laypersons are appraisers who may have a contemplated future interest, by way of commissions or other compensations, in an object(s) which is the subject of an appraisal assignment. Mainly, this applies to art galleries, antiques shops, auction houses, individuals and related entities, who are, simultaneously engaged in sales and appraisal services.
The simple reason being the possibility of bias on the part of the appraiser, as there exists a possibility of anticipated future financial gain above and beyond their initial appraisal fee.
The duality of seller and appraiser is made manifest when acting as an appraiser who has given an opinion of value pivots, becomes the dealer and makes an offer or accepts an offer to buy or take on consignment an object(s) at a price equal to or near their previously rendered value. Needless to say, this may be the epitome of questionable conduct.
After you have employed an appraiser, and they are conducting an examination keep in mind that you are the client, and your role is to ask pertinent questions, not the appraiser. A sure sign of an appraiser's unfamiliarity or ineptitude with the objects is when they ask questions such as, "How old do you think it is? What do you think it's worth?" and the all-encompassing question, what do you know about the piece?
An appraiser's report must be entirely objective, never subjective. Superlatives such as, extraordinary, one-of-a-kind, exceptional and the like are the domain of a seller and not a professional appraiser.
Moreover, words such as bric-a-brac, vintage, nick-nacks, and other colloquial descriptions are the domain of a dilettante, not a trained expert.