It really, reeaaallly depends on both the personality of both the cat
and the beardie. I am a cat person, but I have both extremes of the cat spectrum living in my home so I can offer both points of view.
My beardie, Diesel, is pretty chill and generally fearless (so far). Never bearded or hissed, always moves in a calm, slow and controlled manner around the cats. He is a year old. We have 2 cats in the house. The first, Sasha, is 9 years old and has always been a very laid back and well behaved cat. Doesn't scratch stuff, waits to be invited up before jumping on stuff, comes to her name (??????? I don't know either), takes baths with relative dignity and grace for a cat (warbles in misery but makes no move to get away), has chewed some headphone cables I left right in front of her but nothing else, is there waiting for me at the stairs after work, and loves snuggles (if I try to pull away from a belly scratch she'll gently grab my hand with both paws and pull it back). She is my cat, and she has been introduced to Diesel in a controlled manner. She does not jump on the top of his cage, mess with the cables or lights, and other than jumping up and hitting the glass front of his viv once during the first week I had my beardie (presumably to try and get a reaction out of Diesel, of which there was none), she has posed no threat. I often have both her and Diesel on my bed with me at night while I relax, and she watches him in interest but makes no threatening movement towards him. She laid down beside him once and fell asleep, that's about it
. She's a good cat and her and Diesel have very similar personalities so there's no conflict.
Now then, the 2nd cat. Her name is Lucy. She makes bird noises, rolls all over the place, scratches up everything, climbs in the Christmas tree, is always underfoot, eats all her food, all the dogs food, all Sasha's food when she gets at it, tore my back and arms to shreds last time she had a
bath, will claw you if she's tired of being pet, and tries to bolt when doors open. 1 1/2 years old and probably should be renamed Lucifer. She is my sisters cat, and she is a terror for other animals. She jumps all over Diesels tank, knocks over lights, and ominously stalks around his tank. When I have Diesel out the does that predatory stalk thing cats do and tries to bat at him and nip him. I keep a very close watch on her, and she is never allowed in the room if I can help it. The same behaviors she shows with Diesel also extend to Sasha (who is 1. much older 2. twice her size and three times her weight 3. The established alpha mammal in the house) so I've come to the conclusion she just has tons of attitude. Diesel maintains his fearless exterior around her, but does get faint stress marks when she starts stalking him and lowers his head. He actively sought to get closer to me once when Lucy got particularly frisky. Because of Lucy's personality, I keep her as far away from Diesel and Sasha as possible because her... rambunctiousness stresses both of them out.
In summary, I don't really have issues with my cats and my beardie, but I keep a close watch on them when they're together and lock the problem cat out of Diesels room.