Hmm.. Well most people who know me pick on me and call me "sherlock holmes" because when I hear something I've never heard of, I research it.. Here's what I found:
Trade refers to the (usually) casual partner of a gay man or to the genre of such partners. Historically the motivations may at times include a desire for emotional fulfillment and admiration, but usually the term referred to a straight man who partners with a gay man for economic benefit, either through a direct cash payment or through other, more subtle means (gifts, tuition payments, etc.). Usually, the concept of trade occurred when the gay man is comparatively wealthy and the partner who is trade is economically deprived. Examples of this include wealthy Englishmen finding partners among deprived Cockneys in 1930s London, or men from the United States and elsewhere finding willing partners in places such as Rio de Janeiro, Brazil, and Bangkok, Thailand, today.Often, the terms "trade" and "rough trade" are treated as synonymous. Often the attraction for the gay male partner is finding a dangerous, even thuggish, partner who may turn violent. That is not to say that people necessarily desire to be physically hurt, but the danger of seeking a partner in a public park, restroom, or alleyway may be exciting.
Another variation is in comparison to regular trade, rough trade is more likely to be working-class laborers with less education and more physical demands of their work, therefore with a body developed naturally rather than in a gym. They will have a less polished style and more "manly" attributes than an office worker or professional businessman. In England, a British soldier, a squaddy, embodies the idea of an exploring the highly developed physique like "an adventure playground."
Okay so I don't know how true this is, but it's better than nothing right?