The problem with dreads, or really long hair, or anything else that puts ones appearance out on the edge is that it is often taken as an expression of extreme vanity ... and that is what puts employers and customers off. If you are in a market that tends that way, e.g., New York, San Francisco, Miami, etc., and an industry that tends that way, beauty, fashion, entertainment, that's fine ... but diving in the islands? I think not.
Not so sure it's a perception of vanity, per se. But that could be one aspect. Whatever it is, the fact that a potential employer may have ANY perception about your appearance - positive or negative - can only hurt your chances of getting the job.
There's a rule I use in advertising and marketing: "Anything that does not SPECIFICALLY ENHANCE the message you are trying to communicate, SPECIFICALLY HURTS your ability to communicate that message." This is true in a TV commercial or a magazine ad, and it's also true in terms of individuals who need to communicate something about themselves.
In an ad, any word, picture, design element, etc that doesn't specifically help drive your message can only do one of two things:
- send a different or conflicting message
- distract from or dilute the message you are trying to send
Same is true of personal appearance when it comes to seeking employment. Overall, the message you are trying to send is "I'm the right person for the job." Unless you're looking for a job at a Rastafarian dive shop, wearding dreads will either...
- send a message that you might NOT be the right person (whether that's true or not is immaterial, it's about the MESSAGE)
- distract the potential employer, who may be thinking "I wonder how he sleeps with those? Do they make your scalp itch? He looks pretty cool. Maybe I should try them?" etc while you're talking about your expertise and skills
Either way, you have compromised your ability to communicate "I'm the right person for the job."
And it's not just things that might risk being perceived as a "negative" from a societal standpoint that can hurt your ability to send your message. I have a friend who's currently looking for a new job, requiring him to do the whole "interview thing" for the first time in 20+ years. He was asking about what kind of suit, shirt, tie, etc.
In counseling him I offered the great advice I was given many years ago about what to wear: "Think about it this way: After the interview, they should vaguely recall that you were well-dressed, but have no specific recollection of what you were wearing." Essentially, if they remember your tie, then either you didn't say enough...or your tie said too much. Neither of those helps you.