I live in a state with very high humidity. Thus I prefer methanol for ion laser optics. Acetone tends to retain moisture as it evaporates. Ion Laser, and Ultrafast optics tend to be slighly hydroscopic. I use acetone for removing stubborn dirt/grease then clean with methanol.
In emergencies, I will use a very good grade of drug store hydrogen peroxide for very stubborn films such as fingerprints on optics, but I expect the optic to retain water. FRESH H2O2 from the drug store comes with very pure triple distilled water, so its not so bad. REPEAT, that is for emergenices, or if I get caught out without a cleaning kit, or cant get one, as if I fly to SELEM or something.
I use very high purity methanol, and I work hard to get small, legal, amounts of it, shipped under argon.
I prefer drop and drag with Kodak or Thorlabs lens tissue. I wont use the cheap camera store tissue, I've had too many "stones" in it.
Second choice is wound wooden stick swabs with no glue. Pharmacists, if told why you want them, plus a business card, will sell you sealed sterile packs of them. They get flushed/washed with solvent quickly before cleaning the optic.
Camera store lens cleaning gunk is a detergent and degreaser, and its OUT as far as I'm concerned.
Some non-cavity optics would get first contact, but I cant afford the US version, the patent in the states has not ran out.
Note, very little of the above applies to CO2 -FAR IR optics. In fact since my day job system has a tunable beam at 4.5 microns, I'm going to have to find a way to do the far IR optics, possibly plasma cleaning them.
Dont get me started on all the funky over-reaction stuff since 9-11, its cost me a fortune in lost business. Attention US Government, MY Lost business = LESS tax revenue for you. Plus you'll have to pay welfare/medicare/Social Security for me when I'm older, because I can save less money for retirement.
Steve