Yep i believe TT MP 10 is painted red as there is a small paint chip at the back side (gun storage part). Takara has been using a high quality plastic that makes it stant out usually against Hasbro version especially their blue and red (and yellow for bees) which usually has a sparkly coat or layer.
Unless Nissan will be specifying a certain shade of Red which Lamborghini specified for Lambos as well as the specific yellow for Tigertrack, we may certain see Ironhide unpainted as well as Ratchet like Wheeljack
TT had some quality issues which I believe most luckily do not notice but paint usually cause more issues (bubbles, smudge, uneveness) and more expensive.
With a larger demand for MP nowadays TT may have chosen a safe side while saving heaps of bucks in the process by not painting MPs![]()