We charge per run minimum call out is £45 for a front of terraced house, we do quote blind but normally take a look before giving price, check access and to see if they are full of weeds
Got a camera, after four years of clearing gutters it's surplus to requirements, you can tell by feel if it's empty, but I do offer an inspection service which has only been taken up 3 or 4 times as most just say get on and clear them
Darran