Because the task of washing Locs can be a daunting one, its tempting to turn a blind eye to the need for a wash. If someone genuinely asks you when was the last time you washed your hair because they say it appears dirty, it probably is. They are probably not being mean but just can see what you don't want to.
The number one comment #CleanLocs client's make is that their hair feels lighter after having a SteamWash'n'Loc. If you find that when putting your hair up it feels heavier than normal it's likely filled up with dust, residue, pollutants, oils, butters etc which is weighing it down. On their own, these factors don't seem all that heavy but collectively it can add up.
YOU CAN SMELL IT
When your Locs smell anything but fresh, its a good time to give them a wash. As with residue, smells can linger and layer on top of one another cause quite the evolution of funk in your Locs. Often we cannot smell our own smell, the way it is impossible to tickle yourself. So if someone indicates that you're Locs are a little less than fresh, and you can't smell it, try rubbing your roots between your fingers and give that a whiff just in case.
ITS DULL OR DUSTY
Anything that is shiny is so because it reflects light, that includes hair. When hair is unclean it coats the strands with oil, dust, free-radicals, and whatever else your Locs come into contact with. This can cause a dull finish which decreases the amount of light that can be reflected off each strand, in turn giving a dull appearance. Time to wash all that off and restore your Locs naturally lit lustre.
When people get itchy it is because there are tiny organisms that cannot be seen with the naked eye, physically crawling on the surface of your skin. Gross. Since your scalp is made of skin, that makes your head no exception to this fact. People intrinsically scratch their skin as a reaction to scrape the organisms off their dermis to relieve the itch. A better way to resolve this is to wash your skin, or in this case, hair.