This word has an uncertain origin but it does look a bit like a useless lay-about, a person of slightly ill-repute whose crimes are equally petty and minor. Referring to someone as a “scallywag” these days is likely to get you quizzical stares or perhaps a more bellicose response if the target senses a certain negativity in your constant braying. So if you call someone a scallywag, do so in a lighthearted and whimsical way, lest you happen upon a mean-spirited etymologist or reclusive crossword puzzle fanatic, in which case prepare for some seriously superficial banter.
whoisfenton 