Five questions, one rung. Climb the ladder of solvents starting from the mildest — hot soapy water — and escalating only as far as your residue actually requires. The first rung that works is the right rung.
pick the closest match — the chemistry of the residue decides the rung
The ladder works because different residues need different solvent chemistries. Polar contaminants (water-soluble adhesives, sugars, fingerprints) yield to alcohol and water. Non-polar contaminants (sap, tar, oils, butyl) need mineral spirits or naphtha. Cross-linked adhesives need d-limonene. Look at what's on the window and pick what fits — if multiple categories apply, pick the most stubborn one.