So one of the reasons why people are put off dreads are due to the fact they think dreads are dirty.
The reality..... Dreads are cleaner than real hair if washed regulary. YES YOU WASH DREADS!!!
Basically there is special dread shampoo which leave no residue in the hair. Residue is in most if not all usual shampoo and conditioner, its the part of the shampoo/conditioner which stays behind coating your hair which then makes it feel smooth and shiny. The hair then tries to get rid of this coating by releasing grease from the scalp to try and clean the hair naturally, hence why if you use normal shampoo and after not washing your hair for a few days your hair will be greasy its due to your hair trying to clean all the shit you ahve put all over it.
The difference for dreads is that you dont want your hair to be smooth and slipperly because they knotts wont stay in to get over this issue residue free soap was created. This leaves nothing on your hair at all when it washes out this means that your hair is clean and free from anything. Due to this your hair doesnt get greasy because it isnt trying to get rid of the residues which you would usually coat hair with. Due to this people with dreadlocks do wash their hair with residue free shampoo, however nowhere near as much as normal people would. Infact i wash my hair about once every two weeks, because they dont get greasy and i only really wash my hair if my scalp starts to get itchy.
To read up more on the issue here is a link to DreadheadHQ one of the best suppliers of dread products out there.
So moral of the post.... DREADS ARE CLEANER THAN NORMAL HAIR!!!!