RN
Here is the awkward thing at the centre of this category: the claim it is built on cannot be verified from the footage, by anyone, ever. Not by you, not by the studio, not by an expert. What is on screen is a performance of a private event, and there is no shot that settles the question.
Everything interesting about the genre follows from that. When a claim cannot be proven, the market for it turns into a market for signals — and the signals are what you are actually choosing between.
The authenticity signals, and what each is worth
The unbroken take. A scene that does not cut for several minutes around the moment in question is making a real commitment, because editing is the cheapest way to manufacture anything. This is the strongest of the available signals and it is still not proof of anything except that it was not assembled from pieces.
The unflattering angle. Wide, static, badly lit, no reverse. Studios spend money to avoid looking like this, so looking like it deliberately is a claim. It is also trivially easy to imitate, and the imitation is now common enough that the signal has weakened considerably.
The aftermath. Scenes that keep running afterwards — where nobody resets, the conversation is ordinary, the energy drops — are doing something a scripted structure has no reason to do. Of the three, this is the one that is hardest to fake convincingly and the one most often cut for length.
The runtime. Anything that arrives at its climax on a schedule is scheduled. Not an accusation, just arithmetic.
None of these is dispositive. Together they are a reasonable heuristic, and the reason to name them is that they are what the "real" and "amateur" tags in this category are gesturing at — badly, and without agreement about what they mean.
The tag that gets welded to this one
Squirting and orgasm are indexed as near-synonyms across most tubes, and they are not the same thing. Plenty of scenes tagged one contain only the other; a great many contain a claim about both.
That conflation is worth knowing about for a practical reason rather than a pedantic one. If you search either term you get both populations back, and if what you wanted was specifically one of them, roughly half your results are noise. The tags will not separate them because the taggers do not, so the separating has to happen at your end — usually by finding creators who are precise about their own descriptions and following them rather than the tag.
There is also a large volume of material in both tags where the claim is doing all the work and the footage is doing none. That is what the heuristics above are for.
Why the amateur half behaves differently
Self-produced and couple-produced material sits in a different position on all of this, for a structural reason: nobody involved is being paid per scene to deliver a specific ending.
That removes the incentive that distorts the studio version. It also removes the production discipline, so what you get is longer, less legible, and much more variable in quality. Whether that trade is worth it depends entirely on what you were after — but if the authenticity claim is the thing you care about, it is the only half where the claim is not also a sales pitch.
Where to look
The directory's amateur section is the most productive starting point for the reasons above, with free tubes for breadth and the squirt cams section for the adjacent tag, which is at least honestly labelled when it is live. For the solo side of this, female masturbation is the more accurately maintained category and the better search.