That's a really tired look but okay. It's easier to maintain than a beard and sometimes more acceptable to the conservatives. but if you are goint to grow a mouthbox vandyke, grow some 2-3 inch sideburns. Having a vandyke without sideburns looks amteurish and even silly.
Should I post some pics of this hapless look.
Other "Vandyke mishaps":
1 - Keeping it the hair less than a cm short.
2 - Trimming too much of it away. The long thin line effect or pencil thin effect. Unless your clothes and "look" matches this, it looks really silly. The paler the skin, the sillier.
3 - Manicuring the chin hair to point or jut OUT instead of growing down.
As soon as I get a camera, I am going to post my beard growth. After I do, I think I am going to go with the old school vandyke. Right now I have a full beard, but I keep the jawline area trimmed shorter than the vandyke area. The hair between the chin and sideburns does not grow as thick on me and looks kind of crazy if it grows too long.