It's generally used by non-scientists to refer to scientists. People don't tend to use it to refer to themselves (though a few might, in a humorously self-deprecating fashion).
It might have a dismissive or mocking connotation, depending on the intention of the person using it. I guess in the worst case, its use could be described as 'othering'
English is not my mother tongue. When I reached the word boffins I stopped and opened the OSX dictionary which gave the right perspective... Because I instantly related boffins with buffoons which has a totally different meaning and didn't make any sense to call F1 engineers buffoons ?! It's okay if it comes from Archimedes, Francis Bacon and another 10-15 fellas I guess because it's kind of relative... But if I were an F1 engineer, I would had a hard time accepting such a degradative term from anyone else!
ps. Funny how fast all these vivid thoughts crossed my mind in less the 2 seconds.
Hey, the same thing happens with native English speakers. I just heard a radio spot where someone was reprimanded for using the term "pussyfoot" at a meeting.
Don't be silly. Other than perhaps in a school playground where _any_ word said repeatedly enough can be considered abusive, boffin is not word that anyone can take offence from really.
In my experience it's actually rarely used negatively (ymmv of course) - I only really hear it when the context is "these people (the boffins) do something about which I don't understand", so it's almost self-deprecating to call them boffins. On the otherhand it's also not particularly positive, either.
As an example: Stephen Fry uses it, and he is a.) a geek and b.) not the kind of person to insult people for that kind of thing - when he uses it he always just means that they're people doing something complicated that he doesn't know about.
