What the inspection actually records
A pre-purchase inspection has no fixed scope. What gets examined is whatever the buyer, the seller and the inspecting facility write into the agreement, which is why the scope letter matters more than the label on it. Most go past logbooks and borescopes into a condition survey: cabin, paint, windows, seals, gear bays and belly, recorded in photographs and video as they stood that day. That record is the baseline for everything argued afterwards, including who pays for the crazed window, the flaking belly paint and the split bolster. Appearance work changes the images. The timing of a detail is a commercial decision, not a cosmetic one.
What a detail can hide, and for how long
Dressing on rubber, polish over paint and a heavily fragranced cabin all hold for weeks, which is longer than an inspection takes. A weeping seal reads as a clean seal. Filiform corrosion works underneath paint, and the remedy FAA AC 43-4B gives is environmental rather than cosmetic: keep the aircraft below 70 percent relative humidity and wash off the acidic airborne contaminants that feed it. A polish changes how that paint reads without changing what is under it. The belly is the clearest case. Hydraulic fluid, fuel and exhaust soot leave streaks that trail aft from wherever they start, and a wash takes the pattern away before anyone has photographed it. Those soils trap corrosive material against structure, so they are worth removing for the airframe's sake. They are not worth removing the week an inspector is booked to look at them.
The failure mode when a buyer details first
Purchase agreements commonly put airworthiness discrepancies on the seller and leave cosmetic items with the buyer. Whether those cosmetic items come back to you as a credit depends on what you negotiate, and you can only negotiate what the report names. Every defect your own detailer removed first is one the report cannot name, because no inspector writes up what is no longer there. Buyers do this with good intentions, because the aircraft arrives dirty and they want it presentable for their own crew, and they pay for the impulse twice: once in the credit never argued, once in the invoice. Read your own agreement before you book anything. The split is whatever that document says, not whatever is customary.
The failure mode when a seller does nothing
Presentation is read as a proxy for care. An inspector who opens an odour-free cabin and finds gear bays and a belly clean enough to read forms a different view of the maintenance culture than one who finds years of accumulated soil, and that view colors how every marginal item is characterised. The wording of a borderline finding is a judgement, made by people who have just spent days inside your aircraft. Presenting well is legitimate. Presenting in order to conceal is not, and it surfaces at the next wash.
What changes the answer
Three things move it. First, correction is consumption rather than presentation. Aerospace clearcoat builds to roughly two to two and a half thousandths of an inch, correction spends film that cannot be replaced without a strip and repaint, and a full strip and repaint is about five to seven weeks out of service. Nobody should spend that film to improve a photograph in someone else's report. Second, cabin materials have memory: Gulfstream's own completion center maintenance procedures warn that silicone-based polishes leave a residue on the urethane wood finish that can prevent a later repair, so a rushed pre-sale shine can hand the next owner veneer that cannot be touched up. Third, if the airframe is polished rather than painted, the cladding on Alclad sheet is only about two to five percent of the sheet's thickness, and aggressive or repeated polishing can go through it to the copper-bearing alloy underneath. That is not a decision to take at a deal's speed.
Why the sequence we recommend costs more
Detailing after the inspection is the more expensive route for a buyer and we still recommend it. You are paying an inspection team to find things. Paying a second team to remove them first is buying the same information twice. It also helps to be clear about what is being bought. A wash is hours, one technician and one product, and it is a different product from a detail rather than a cheaper version of it. A detail is crew-days treating leather, Alcantara, veneer lacquer, stone, plated metal and acrylic as separate problems, each with its own chemistry, which is why the Gulfstream handbook carries separate procedures for wood, granite, Lexan, vinyl laminate, plating, stainless steel, leather, vinyl, rubber, carpet and fabric. Add correction and brightwork, and carry it on aviation-specific insurance at limits an FBO will accept. A full interior and exterior on a midsize jet at a professional standard is a five-figure job before condition or deadline are factored in, and the worst version of that spend is the one made on an aircraft you did not end up buying. Do it once, after closing, against a list you already trust.