"STANDARDS RULE 1-2, PROBLEM IDENTIFICATION
In developing a real property appraisal, an appraiser must:
(e) identify, from sources the appraiser reasonably believes to be reliable, the characteristics of the property
that are relevant to the type and definition of value and intended use of the appraisal, including:
(iii) any personal property, trade fixtures, or intangible assets that are not real property but are
included in the appraisal;
(g) When personal property, trade fixtures, or intangible assets are included in the appraisal, the appraiser must analyze the effect on value of such non-real property assets."
If you are not including personal property in the appraisal, I would avoid of modifying your value based on the presence of personal property on the subject, regardless of whether it is a purchase, refi, or pre-foreclosure appraisal. The definition of market value you are developing an opinion of very likely does not include a provision to consider what will happen if the lender forecloses on the property.
Reconciling to a lower value because the personal property is present is including the personal property in the valuation, and you then have to report what impact that inclusion has on the value. The most I would do is as Vermonter alluded to...make an assumption that the junk has not contaminated the subject in any way and then appraise it as if the junk wasn't there, and make it clear your valuation does not include personal property as part of the subject.