Not thorough or detailed.
Because he is so sketchy, I always think that he is up to something.
Disturbing or unnerving, often in such a way that others may suspect them of intending physical or sexual harm or harassment.
Roughly or hastily laid out; intended for later refinement.
Resembling a comedy sketch, of sketch quality.
Of questionable or doubtful quality.
Suspected of taking part in illicit or dishonorable dealings.
Not fun.
Lack or absence of fun; funlessness.