Hillhopper and TNhunter have given you some really good information that you can use in hunting, digging and maybe even growing Ginseng, if you decide to do so! I will just add a few things and hopefully not take away from anything they said. The main reason that Ginseng doesn't usually grow on most South facing slopes which would also include most Southeast and Southwest facing slopes is as they stated due to too much sunlight but also due to these slopes generally being the dry sides of the mountains, ridges or hills. However, this is not always the case as has been somewhat stated already. It depends on the size, slope or steepness of a mountain or hill, the trees and amount of canopy and amount of moisture that is retained in the ground on these. If the surrounding mountains, ridges or hills are high enough and sometimes steep enough to block just enough sunshine off parts of other slopes and there is enough moisture retained in the ground, then Ginseng and it's companion plants will usually grow on these other slopes and may even grow in the bottoms of hollows and sometimes even low down on the mountain, hill or ridge of the one's providing the blocking of too much sunlight. By the same token, even without the higher and steeper mountains, ridges or hills to block some of the sunlight, if there is enough of a canopy and retained moisture as well on these slopes, Ginseng can and sometimes will grow on them and flourish. Another plus to Ginseng growing on these slopes, is if there is a constantly running spring, branch or stream in the hollows of these which supplies moisture to the plants and soil on their' ridge sides by way of evaporation, condensation and even fog. Therefore, if you happen to find some mountains, ridges or even hills that meet most or all of these conditions, it would be wise to not to discount them and venture into these locations for a look.
Frank