Say so, and say why

When the material cannot support the assessment that was ordered, say so in one message that names the specific gap and offers a way to close it. Producing the assessment anyway and hedging inside it is the expensive option, because a hedged assessment reads as weak work rather than as a limited submission.

The usual causes are material that is too dark, too tightly framed or missing the angle the assessment depends on, or a brief asking for something the material could never show.

Name the constraint, not the buyer

There is a large difference between "the images are not good enough" and "the second and third images are lit from behind, so I cannot read texture, which is one of the four axes you asked me to score."

The first is a complaint about them. The second is a description of a fixable condition, and it tells the buyer exactly what to change.

Say which axis or section is affected and which are not. Most of these situations are partial: three of four axes are fine and one is not, and a buyer who understands that will usually resupply rather than cancel.

Always attach the remedy

Never send the problem without the fix in the same message.

The remedy is normally one of three, in order of preference.

Resupply. State exactly what would fix it - a second image in daylight, a wider frame, the missing information - and confirm the turnaround restarts from when it arrives. Deliver partial at a reduced fee. Assess what the material supports, say plainly what was not covered and why. Cancel and refund. Fast, clean, one sentence.

Buyers usually take the first option when it is offered concretely.

Do the arithmetic before you offer a redo

A free resupply-and-reassess is not free. It is a second pass at your normal rate, given away, and on a low-tier job it can wipe out the margin entirely.

Fine once, expensive as a policy; the tipping point is the one in when a revision is worth doing. For anything below your standard fee, resupply once and price the second one.

The situations that are not about material quality

Two categories look like "cannot assess" and are actually something else.

A brief that asks for a judgement outside your competence is not a materials problem. Say you do not do that, in one sentence, and refund - the standing case for it is staying inside what you actually know.

A brief that asks for anything resembling health interpretation is neither. The output there is one neutral sentence recommending a clinician and no assessment, regardless of how confident you feel. The NHS takes the same line with the public: its guidance on penis lumps and spots (NHS, 2024) says "Do not try to diagnose the cause of penis lumps or spots yourself."

Why the guess is the worst option

Whatever you write is a document with your name on it that the buyer keeps. An assessment built on material that did not support it is wrong in a durable, quotable form.

Worse is guessing and happening to be right, because you learn the wrong lesson.

Where the limit is genuinely photographic, the constraints are well documented and not a matter of your judgement at all - what image conditions do and do not permit is worth being able to point at, because a cited constraint reads as expertise while an unexplained one reads as an excuse. The same applies when the ask needs a measurement you were not given; the site that owns the gear and conventions is the right reference, and estimating a figure from an image is exactly the guess this post is about.

Buyers, for their part, rarely realise a submission was inadequate until told, and their account of how a commission is supposed to run shows how much they assume the professional will simply cope.

Platform mechanics for partial delivery, resupply and cancellation - which decide whether the options above are actually available to you - are on Rate Cock's judges page, and they are worth reading before the submission that forces the question arrives.