i have personally been scammed by some who don't end up looking like the person i saw in photos, and it turns out, that these same people are 2x more likely to not render a service. surprisingly, i haven't cancelled in these situations, although i will definitely do that next time around.
in terms of checking for these catfishes, i think you are basically trusting your gut feeling and looking for the common thing, like enhanced photos or something of that sort. moreover, when the photos are too compelling you should try to be twice as careful. i recommend looking up the photos and trying to validate everything. reverse image search is good. google lens is a good way to do that. and sometimes you have to go the extra mile to find the image online, meaning you look up all their images multiple times. The reverse image search on Google Lens lets you zoom into specific areas of an image. This is particularly useful because you won't always find a match with the entire image, but if you zoom into a detail like a face, you can usually find what you're looking for. so i will try to lookup the image effortlessly sometimes to make sure i don't get scammed.
often times, it's really hard to tell, and you're basically at the mercy of the poster. you have a decision to make when you see them. if you really wanted to see the person you saw on LL instead of the catfish you met in person you're better off cancelling.
i hope this helps. if you have any questions about anything please let me know.