They usually have a companion mercenary as a bodyguard, who are armed with decent firepower. There is also usually one brahmin per merchant to carry their baggage and inventory. Occasionally two traveling merchants will travel together, each with his own merc and pack brahmin. Heavily trafficked areas for the merchants include the Mojave Outpost, Novac, Freeside's North Gate and near the Crimson Caravan Company.
Mojave Outpost has a merchant who never wanders far from the location, if he is not at the outpost he is east of it at the bottom of the highway.
A lone merchant with no mercenary guard will appear at Boulder City the first time that location is visited; he will travel south to Novac, where he will remain at a fixed position at the gate entrance to the gas station. His inventory does not replenish, which eventually makes him useless for trading purposes (see bugs, below).
Traveling merchants do not offer reputation discounts, a good Barter skill is necessary when dealing with them.
Caesar's Legion members are hostile to traveling merchants, and will often kill both them and their guards.
For lower level characters, traveling with a merchant and their mercenary can provide protection from the dangers of the road.
The player can find the static remains of a dead traveling merchant, their guard and a pack brahmin near the El Dorado dry lake, the brahmin is a normal corpse able to be looted, however the merchant and guard are static objects and appear as mauled corpses.
The merchant who frequents the area around El Dorado dry lake may be killed by the giant ants or Viper gunslingers in the area, but will generally survive multiples encounters with them before disappearing from your game completely.
pc A merchant that has been killed by a plasma weapon turns into a goo pile that can be used to initiate a conversation once the merchant has respawned. The merchant can be quite a distance away but the conversation zooms in and initiates anyways. [verified]
pcxbox360 A single traveling merchant can be initially encountered just outside Boulder City, armed with a cowboy repeater and lacking a mercenary escort. This merchant will buy and sell goods, but his stock consists only of what he is carrying and does not change periodically, as with a normal merchant. Furthermore he will travel from Boulder City to Novac only once, and will remain in Novac for the rest of the game. [verified]
pc At least two traveling merchants' inventories are not set to change periodically (or "update") as they should be: the merchant found outside the Mojave Outpost, and a merchant located near the Strip. These merchants will still buy and sell goods, but aside from changes due to sales their inventories will remain the same over the course of the game. This is true even if they are killed and later respawn. [verified]
xbox360pc One traveling merchant may stop near the Poseidon gas station in Novac and remain there for the whole game. [verified]