This is unfortunately usually the case. A collector can always be mistaken or even disingenuous.
The fact remains that Colcord's background and interests make her as authentic a source as any of the other editors (except those who made sound recordings). I don't believe she "camouflaged" texts either - just omitted them.
Harlow and Hugill, to name two, could have enhanced our knowledge - or at least lessened our confusion - significantly if they'd only been trained folklorists as well as singers of shanties. But they weren't. And, of course, neither was Colcord.
Of the thousands (tens of thousands?) of English-speaking sailors who sang shanties between, say, 1830 and 1920, how many wrote books about them? Let's see:
Whall Bullen Harlow King Hugill Rutzebeck
Who did I leave out? (Let's add Davis & Tozer and Terry just to be polite.) This is a vanishingly small (but hopefully not too unprepresentative) proportion of (white) sailors. Certainly less than one in a thousand.