paint scraping

i need some advice, folks. i've been asked for a quote on cleaning some windows that still have paint around the edges from the last time the frames were painted. there are two related problems. first, the frames were inadequately prepped before they were painted and they were heavily coated. chipping the paint off the glass is certain to dislodge slabs of paint that extend onto the frame. second, some windows were poorly installed and the putty extends too far (and irregularly) onto the windows in places. again, i'm in danger of removing chunks if i try to even it up. trying to go in from the perpendicular to create a cut between window paint and frame paint doesn't work because the paint is so thick it cracks.

i'm neither a painter nor a glazier. any tips or secrets on how to deal with this situation? i'm about to tell the owner he needs a painter to go in first and do it right if he wants the paint off, and i can clean after that, or else that i'll clean them but not scrape the paint.

thanks

richard