Why can big beards make a man look immediately crazy?

For the same reason big hair can make someone look crazy. They make you look unkempt.

Robin Williams in Jumanji

What also helps are crazy eyes. Dumbledoor also has long hair but mostly doesn't look crazy.
Fisher King?
- Jumanji

Perhaps your experience with “crazy big beards” is actually with unkempt, long beards.

My face friend is smooth AF and garners trust at the workplace. But ya gotta take care of it. Ya know — hygiene and shit.

It depends on a mixture of features... With the beard, the face, attire, etc. If you have kind eyes, you can have almost any beard and not look crazy. Here are some examples.

1

2

Versus

3

4

Versus

5

6
- I want to look at the pictures and respond, but the formatting of the links as “1”, etc. make it terribly difficult to tap on in my mobile client. I just keep collapsing your comment instead haha
  
  I was able to tap on two of them. I agree that kind eyes help, no doubt. Kind eyes make most people more approachable, bearded or not. So what if we focus just on the beard itself? Is there anything intrinsic to the beard hygiene or perception that matters?
  
  Based on the two pics I could get to, it seems like dramatic angles, beard balm, and lighting might be beard-specific differences between your groupings. Those factors all can significantly impact the beard vibes.
  
  Way too much thought on this this morning. Thanks for hanging out with me on this one! :P
- No. 4 really has that "beachy waves" style beard.
  
  Side note, I'd kill to be able to grow as thick a beard as No. 2.
- Edit: Nevermind they didn't show up and aren't in my edit now.
"Hygiene and Shit" is going to be the name of my next album.
Hobo vs. Santa vibes.

Big beards can alter facial recognition and obscure expressions, making someone look more unpredictable or wild to observers.

It's like anything hygiene related. If you put effort in it attracts people. If you don't, it repels people.

Because you have a subconscious preconception about beards.

It is true that beards can hide expressions, making it harder to read someone, which can reduce "trust". But that's only part of it. Your idea that it makes them look crazy is all about your ideas of things.

You're probably basing it on the unkempt nature of people that aren't able to function well. The homeless, people that are "crazy" or otherwise behave unusually, that kind of thing. You've developed a connection between two things that aren't really connected. An unkempt beard only means that the beard isn't being grown to be socially conforming. The fact that people that are unable to socially conform rather than choosing not to tend to be less capable of maintaining a beard to social standards is a separate issue.

Don't get me wrong, it's a fairly common thing to have that preconception. I have a big ol beard and sometimes catch myself spending extra time evaluating the threat level of someone that's ragged.

Don't worry about it. We all have preconceptions, it's how human's minds work. Just keep yourself aware that you can't reliably trust preconceptions.

I don't know about crazy. Big beards make men look hot

Because people are really good at picking up stereotypes from fiction.

Gunna plug !beards@feddit.uk - cause at the moment there's only one sad beard there.

Currently travelling and managed to get my beard in check almost a week ago. Will probably be untouched for another month. My hair is also getting long. I'm afraid of weirding people out but every time I get a haircut and beard trim + wet shave they always make my beard too short and it's annoying to grow it back to how I want it. I generally keep it reasonably short and neat but let's see what happens after this next month of travel.