+1 to blotting up the alcohol before it dries.
But the no clean paste that many pcb manufacturers use, defacto, is difficult to clean. The no clean flux residue may contain very little resin and a lot of ionic residue. Ionic residue (the white stuff) does not dissolve in IPA. You might experiment with other types of cleaners. But using a brush or an ultrasonic cleaner might be necessary.
Rosin flux residues also contain these same ionic components. But they are bound up in a much larger volume of resin which dissolves in alcohol. When the resin is dissolved, it leaves most of the ionic residues floating around, freely/loosely, in tiny chunks (little white specs) that are fairly easily rinsed/flushed or brushed and blotted up off the board. If you view the board under a microscope while cleaning it, the alcohol looks like the contents of a snow globe. But when the resin component is very little (as it is in most pcb manufacturer no cleans, for esthetic reasons), the ionic residue is concentrated enough that it bakes itself to the solder mask in large, contiguous patches and is physically bonded there. It doesn't want to let go after the resin cap is dissolved.
Think the difference of spilling crystallized/powdered sugar on the counter and cleaning it off vs applying sugar water to the counter and letting it dry and harden. Then trying to clean it off. (With a solvent that doesn't dissolve sugar.)
If you were to you use this style of no clean for rework (not all of them are this annoying; this type of no clean is designed for stencil application in precise amounts), you will have a bad day when you apply alcohol. As soon as the resin is dissolved, the copious ionic residue will swell with the water in the alcohol and verily clog between the pins of ICs. With rosin flux, you can't use too much because of the bulky resin component. There's only so much residue that can remain between the pins before it flows out across the board, and it's mostly resin that easily dissolves in alcohol.