The phrase ‘boring brown furniture’ is usually used by those with an experience of interior movables limited to what one’s grandmother had in the parlor. Frankly, our modern opinions about muted color and patination are not unlike those Sir Joshua Reynolds had about the Italian quattrocento painters- the old masters of his day- whose work, several centuries on, caused Reynolds to mistake the depredations of age with the artists’ original intent. The restoration of the Sistine Chapel would have shown Reynolds, as it shows us, that people have always loved color. The 18th century was no exception. While brilliance was possible with exotic wood furniture- figured mahoganies, satinwood, calamander, rosewood- the list goes on- the effect could likewise be achieved to dazzling effect with painted furniture.
It is difficult to know how much painted furniture existed in fashionable 18th century interiors, because comparatively little survives. The why of this is difficult to know precisely, but changing fashion had something to do with it. The rarity of exotic wood furniture in 18th century England made it available to the few. Improved transportation and the use of machine tools for mass production made exotic wood furniture more available, and consequently cheaper, with the fashion in Victorian times moving toward, almost exclusively, wood finishes. 
As well, painted finishes are, well, painted on, and easy to damage, and, rather than repair, painted furniture was generally discarded. Since the paint application was on common woods- beech and coniferous woods, generally- once scruffy, the pieces were easy to throw out, or use as firewood. Gilded pieces were the exception. Something to bear in mind, though- pieces we see as completely gilded today were often originally painted, with gilt sparingly applied to accent certain portions of the decoration.
One of the most popular painting methods was ‘japanning’- the generic term for the European manner of using painting techniques to try and imitate Oriental lacquer. Ironically, japanned pieces are frequently more exotically decorated than the Oriental pieces they sought to imitate, and certainly use a broader range of colors. For an 18th century tradesman whose knowledge of the exotic east was limited to what he found in the shop’s pattern books, an Indian was an Indian, whether south Asian or North American, and Indians of any geographic locale could reasonably share the same decorative space as Mandarins.
Paint effects for their own sake could become quite sophisticated, as witness the Regency armchair pictured. The antiques trade uses the term ‘ebonised’ frequently, but inaccurately, to indicate that a piece is painted black. Of course, ebony is not black, but a deep brownish gray, often with lighter brown striations. This chair is painted precisely this way, suggesting fine quality macassar ebony.