Well let me voice my two cents here.
Any paint, will not only show but enhance any flaws in the surface being applied to. A house will lean if its foundation isn't properly done, so holds true with paint on plastic. Mastering each step of the process is critical to any scale modeling project.
Two ways to help reduce the amount of surface flaws visible in NMF paint schemes. Polish out all of the imperfections. Remove them! Or level the surface as much as possible using a good primer, sanded and polished to ease the roughness in texture.
Each paint has different characteristics. Each of the two paints I produce...Spray Metal and Talon have similar results but they also differ. Spray Metal is an enamel paint, and covers much like the lighter colors of other enamel paints. It dries fast and can be tinted using enamel paints. Its sheen can be increase by polishing.
Talon is very similar, it is an acrylic paint and dries with a bit glossier of a finish than Spray Metal does. It is also self leveling and self sealing! It too can be tinted using acrylic colors and also can have its sheen changed by polishing.
Polishing...with my Polishing Powders which gives you a huge variety in tonal contrasts. Or, by using a polishing stick, paper or compound to change the luster of the finish.
So many are afraid of doing NMF on a subject, but it is easy if you don't rush the process or add unnecessary complexities to it. Doing a NMF is no different than just applying any painted finish. Do each step of the process properly and you'll have the results you want. Screw up or omit one and you'll see the error of your decision afterwards...often too late to correct without major effort.
However, with Talon, it can be removed by washing down the model or the area with Windex. If you're using Spray Metal, just like body shop does to repair an area on a car, follow the same procedures, then reapply the paint to that area, blending it in. You'll probably never see where you made the repair. Often a blemish can be cleaned up using a polishing stick and the area resprayed.
So if you're results aren't what you expected when using a NMF, chances are if you look close at the other schemes you have done using "regular" paints...they probably have similar issues too.
FOIL! I used to do my NMF subjects using foil. Some turned out nice, others not so. Foil is labor intensive and is subject to the same issues paint. Any surface flaw will show through the foil, unless you are using really thick foil. A grain of dust, a speck of dirt will show up as the foil is embossed onto the surface.
Adhesives which crystalize will also show as rough areas through the foil. The tools used to apply foil are often too rough on the surface of the foil and leave scratches and rub marks. One of the most noticeable issues with using foil is similar to panty hose. When the foil doesn't contour to the surface it puffs out. When it is forced to contour it often gets a run or stretch mark from the embossing.
Ever see a pair of legs which have been wearing hose all day? The knees begin to pucker and don't contour well. This happens to foil too. As the adhesives cure, the bond to the foil lessens and allows the foil to bag or pull away from the surface. Raised details are really prone to this. A thin crisp panel line will often be wide and ugly because the foil is too thick to contour properly and if it does, the glue can't hold the tension. A really great foil job is rare. It takes a true master modeler to do one properly.
Foil is also subjective to environmental factors...oils from your hands. Solvents. Paint bonding issues...remember aluminum is one of the hardest metals to get paint to adhere to...requires a specific primer.
Back to painting NMF. If you're not happy with the sheen or tonal color of the NMF you need to experiment with tinting and polishing. You also have to determine what phase of the subjects life cycle you are replicating. Shiny new, well weathered and worn...or grossly chromish looking and plan accordingly to get the results you are seeking.
Hope this helps. You can always drop me a note and I will be happy to discuss and make specific recommendations.