I'm about to clear another swirl with spray paint CC so if it something that can help out please go there!
Ok, I was going to get all technical about paint properties and BS but I will give it to you in a nutshell.
Spray clear is non catalyzing paint...meaning that its requires 'air' to 'dry'.
The problem is that rattle can paints are designed to make something look glossy. That would be all fine and dandy if you only looked at your guitar!
A clear coat on a guitar is designed to protect the guitar FIRST AND FOREMOST!!!! True that looks are important but a guitar is a tool and not just something hung on a wall.
People try and get build with rattle cans by applying tons of thick coats....well....they find that months, years or more that the paint feels 'goopy', will mar with a fingernail and god forbid any type of chemical cleaner is applied! (<were a real CC would just laugh at it), because the paint will never dry.
With a 2 part clear coat you can apply as many coats as you want....hundreds if you wanted!!!! You only need to allow the clear to flash for X amount of time and apply another.....and....depending on spec, how hot you mix the clear, RH and temp it will dry fully in 8-24 hours! NO sanding, NO waiting, NO drips, perfect adhesion!!!
Now you have the build needed to protect the guitar, the paint is dry and you can now sand and buff!
IN THE REAL WORLD....
Lets say you want to do a solid color guitar.
With modern paints, formulated and designed to work together....
You can spray your primer, wait till flashed (10 mins for example), spray your color on the wet primer, wait till flashed, and then spray multiple coats of clear with a flash cycle between each coat.
All the paint 'bonds' together and is as good or better then the OEM finish on the guitar. You cant do this with rattle cans due to compatibility issues...try it and you will get a catastrophic paint failure.
Because can clear coats have solvents in them.....and the base coat you spray used solvents, you can cause your color coat to melt because the fresh solvents in the clear re-liquify the base. Ok, it may not cause any issue...unless the base and clear have a chemical incapability!!!
Again, to sum it up....
Rattle cans were never designed to protect...only shine.
Rattle can paint was only designed for a few thin coats...no more.
Rattle can clears have tons of solvents to extend shelf life....making true build very difficult and they wont dry properly.
Most rattle can CC does not have UV protection (*some newer ones do) and will yellow in a few years.
You can buy a small HPLV gun, regulator and small compressor for a few hundred....expensive....but so is your guitar. Plus....there are ten million other things you can paint once you get this stuff (a car or motorcycle for instance). It will also open a world of specality paints, technique, metal flake, fades, sunburst or wtf ever you can come up with.
Some will argue with this and swear that rattle can paint is just as good.....some people think kraft mac and cheese is gourmet too!
NO SPRAY PAINT FORMULATION IS AS GOOD AS THE MODERN HIGH PERFORMANCE ENGINEERED CLEAR THAT CAN BE PURCHASED AT YOUR AUTO PAINT SUPPLIER!!!!! PERIOD!!!!
At the guitar factory I worked at.....we used Sherwin William automotive paint exclusively.