I used to do all schools in the old Inner London Education Authority, the staff rooms were disgusting, everything covered in nicotine slime. There were about half a dozen firms all speciallising in schools and each employed maybe 10-15 men. We tried everything we could, soap, detergent, vinegar, you name it. Nothing worked, always left smears. Then some bright spark tried plain, ordinary water.........
Bingo!! For some reason plain water dissolves the stuff far more effectively than any sort of solution, and when you squeegee it, it comes off clean. If you squeegee after swabbing with soap solution there's always a scummy, slimy residue.