So I found something interesting

I had no idea you could actually find your retainer out in the field but I just did now. It looks exactly like my retainer with his butlers costume on. Interesting. Anyone else know about this?

http://i.imgur.com/HoS4Kbq.jpg

Yes, they added this 2.3 if i recal, its based on how may retainers are on active duties at the time. They can also be found fishing near horizon and buying items at the pvp founters occasionally.

But the ones that steal house roofs and furniture are apparently very stealthy.

All retainers in the open world wear the same gear, regardless of what you give them in "retainer appearance". You can see anyone's retainer too as I've encountered a female fishing at Oschon's Torch and a male Lala mining in Welwick Wood. Both were bitching on about how badly they were treated. xD

I love taking pictures of retainers out in the open.
Once, I saw a lost Hyur walking along a path...he apparently had no idea where to go.

Damn I want to find mine now.... does it matter what venture you assign?

Yeah, you can definitely find retainers out in the field, but as Culfin mentioned, they're always dressed in the default retainer outfit and never what the player might have equipped on them. I've seen them plenty of times along the path that runs past the Gates of Judgement between Whitebrim and Camp Dragonhead in Coerthas Central Highlands - interestingly they are always MRD class (based on the great axe they wear on their backs), which makes me wonder if retainers are sent to only specific areas depending on what you assign them.

But yes, you can definitely see retainers out in the field (which makes you wonder exactly where they're stealing pieces of houses from). ;)

If you find a retainer, do their names show up?

I think the random retainers you see come from people on your friend list. At least, I've seen a very distinctive retainer that belonged to my roommate, and someone on my friendlist saw one of my rather unusual looking retainers. What's strange is that they aren't necessarily doing an activity related to the venture they are on. My roommate's battlecraft retainer was mining in North Thanalan.

I'm pretty sure the retainers are fixed for each zone. I always see Godbert's clone in Northern Thanalan (miner), a Lalafell in Eastern Thanalan (Umbral rock spot) who says "One for the Master, one for me. Easy as taking candy from a rock!", and a Hyur marauder with an aqua pompadour near the Gates of Judgement in Coerthas.