There's a fine line on what's personal and what's personal but necessary to add utility and function to the real estate. A long time ago I learned that in order to appraise the subject, you must first appraise the comps. Essentially and as stated in other posts, did the personal property contribute to the sale price of the comparable? ie, did it sell for more than market because of the personal property, or did the personal property add to the appeal of the comparable and simply enhance the overall appeal?
Quite often people will leave things they won't need for the next property rather than move them (refrigerators, drapes, etc) and leaving them is no real value loss or concession on the seller's part as they have liitle value in the market and there's also the cost to liquidate them and the time, etc.
It's been my experience that most often, such personal items have little if any contribution to the price and may require mention, but not a deduction as such items included in the sale are common. Agents tend to list these items separately and refer to them as personal, which we review in the contratc and have to deal with in the report.
On the other hand, a fully furnished condo/house may be a different matter altogether. If you can clearly identify and separate the value of the items ($5,000 worth of furniture) and verify with the seller/agent/buyer, etc. you need to make an adjustment. However, a used refrigerator or washer/dryer at $500 on a $150,000 sale would be a little difficult to isolate.
Keep in mind 1) the grid is for making adjustments that are reflected in the market, simply because there is a line item doesn't mandate than an adjustment is made if you cannot identify that the market would make a similar adjustment. 2) most MLS listing are not deatiled enough to show personal property that may have been included in a comparable, the agent simply didn't list it or mention it as the item came up in the buyer/seller contract after the itme was listed and hence, you didn't know that the comparable you comparing to also had some minor item "thrown in" to close the deal. 3) the purpose of the grid is to narrow the indicated range of the comparables and that such items can be mentioned (if significant) in the market comparision comments as you weight each of the comparables.
Bottom line, would the comparable have sold for the same price without the item(s) and if not, you may want to comment that it is common in the marketplace to include such items (for many of the reasons cited in the posts above) and no market derived adjustment could be extracted nor was it warranted.