Nodis, Aiken -
With some loose tongues and a small amount of gold (5), you manage to find out that Garza is indeed a slave trader, trading in all kinds of slaves, including the less savory slaves used in the "private entertainment" business, which is generaly frowned upon yet often overlooked. As are many in such businesses, he's thought to have many underground connections. He operates his business from a large building at the southern end of Rheim, where he offers slaves for rent or sale, as well as running the occasional auction. Some of his slaves are rumored to have previously been business rivals, or those who caused trouble with Garza, but that would be illegal, so most dismiss it at rumor, though a few you speak too are more suspicous.
Back in Rheim...
General public opinion of Garza is that he's pretty accepting of all slaves, and always on the look out for a great deal. He's known to be pretty shrewd, but will occasionaly become fascinated with a particular subject. He's also known to have a fairly steady rotation inside his own personal slave harem, though rumors of it's size seem to vary widely.