Madison police believe car thieves are spray-painting vehicles to disguise them. (Madison.com, 6/21/2019)
For the first five months of 2019, 186 vehicles were stolen in the city, a 17% increase from the 159 stolen vehicles through May last year.
Merriam-Webster defines a verb sense of 'disguise' as to obscure the existence or true state or character of : CONCEAL.
An amateur paint job would make the vehicle stick out like a sore thumb.