I don’t think retyping someone else’s writing and omitting their error makes you look like a dumbass, although I’m a lowly state court lawyer and don’t practice in federal courts so maybe the big time white shoe litigators would disagree. Outside of appellate filings I generally only use [sic] if opposing counsel is someone I don’t get along with or if the error is somehow actually important. If it’s just a typo in a discovery request or something? No need to try to make anyone else look bad by drawing attention to a harmless mistake, because god knows I’ve sent shit out with typos before. Correcting it without brackets may not be consistent with the blue book or whatever academic style, but I’ve yet to encounter anyone (judges, co-counsel, bosses) professionally who seemed concerned with little shit like that.