Most people land on a comparison site already halfway to a decision. They have a treatment in mind, a rough number in their head and three similar looking clinics open in three tabs. What they need is a way to tell those three apart, and the websites tend to make that harder rather than easier, because they are written to sound like each other. A fair number of them read as though the same copywriter produced all three, which is often literally the case.
The useful signals are boring ones. Does the site name individual treatments, or does it group everything under a phrase like advanced skincare solutions? Is there a page per service that describes what actually happens during it? Does the clinic say who performs the work, and whether a consultation comes before treatment or after you have already committed to a package? Are the hours, the street address and the booking method all findable in under a minute? A business that has decided what it is tends to answer all of that without being asked. Photo galleries are worth less than people assume, since they are rarely labeled with how many sessions produced the result or how long after treatment the picture was taken.
For a sense of what the readable version looks like, one small appointment only studio here in Las Vegas gives each of its five treatments a page of its own: a custom facial, microneedling, a sculptural face lifting treatment, a Herbal Green Peel described as botanical exfoliation, and a Red Carpet Facial framed as the special occasion option. The site states that a consultation is part of every visit, lists one location, posts hours of Monday through Saturday with Sunday closed, and takes bookings online. Whether that particular menu suits your skin is a separate question, and not one any homepage can answer.
Which is the limit of the method. A clear website is evidence about how a business communicates, not proof of how a treatment will go for you. The phone call still decides it, and the questions worth asking are specific ones: who will be in the room, what does aftercare look like for the treatment you are considering, how many sessions does the clinic expect for the result being discussed, and what happens if your skin reacts badly to something.
So keep the shortlist short. Two or three clinics whose sites you understood, one call each, then a consultation booked with whichever one answered in plain language rather than in brochure copy. If one of them will not answer those questions before you come in, that is your comparison finished early.