Methanol's one carbon.
Ethanol's two.
Propanol's three with several isomers.
Then it starts getting more complicated.
Ethanol makes you intoxicated.
Methanol makes you blind.
To way oversimplify....things that are soluble in one are soluble in another alcohol.
Presumably camera sensor structures are insoluble, lest they dissolve!
They are very volatile, evaporating into the atmosphere. Anything non-volatile dissolved in them gets left behind after the alcohol has dispersed into the air.
Eclipse, per it's MSDS is mostly or wholly methanol. Pure methanol, without dissolved solutes, would disperse totally, leaving nothing behind.
Pure alcohols are, hence, great cleaners. A Sharpie, on the other hand, is an alcohol with dissolved inks, ergo not a very good cleaner.