Steerpike said
The only way around this is to retrieve the Lordvessel before you visit, then you can warp out whenever you like.

This is actually incorrect. I had the Lordvessel when I visited the painted world and if you select warp from the bonfire it will tell you "you cannot warp from this bonfire, it is cut off from the others." So indeed, the only way out of the painted world is through. When you do get to the end, think hard if you want to take on Priscilla; I'd say of all the bosses I've faced so far she's been the toughest. I couldn't defeat her without summoned help. I believe you can get a special dagger from cutting off her tail, but if you don't care to have that, or her soul-- which can craft a special scythe-- then you can simply heed her pleas and leave peacefully.

The choice is yours!

The Duke's Archives bonfire (post-Seath encounter #1) and the painted world's are the only two where I've seen that "cut off from the others" message.

Pokey, if you go back down the well to where the bonewheel skeletons are I believe you can find a key to open a shortcut (or maybe just an alternate area through the back of that church-ish area) as well as a particular pyromancy or sorcery spell ... I can't remember for certain. It's confusing down there though, quite a maze.

Apparently I need to stop putting off the Tomb of Giants and New Londo. I warped to the Sunlight Altar last night, dropping my summon sign on the off chance that it maybe a spot to do so for taking out the Hellkite Dragon. This was my plan to see how others would go about taking it down, because even now that I'm in the soul level 90s he still stomps all over and toasts me. Well, I was summoned, but not to fight the dragon. I was summoned to fight the Bell Gargoyles. That's right, I'm now being summoned by people who are in NG+!

This is a sure sign that I need to toughen up and venture into new places to satiate the Lordvessel!

I've had some interesting experiences over the past few days. The bad first: waltzing around Anor Londo, as you do, I was merrily invading the guilty-- and promptly being destroyed four out of five times-- until one time where I was taken aback by my invading appearance: I was a red phantom. Now, when you invade as a Darkmoon Blade there are two messages you will receive:

"Invading another world as a spirit of vengeance." -- You receive this when you manually invade someone using the Blue Eye Orb.

"Invading another world as a dark spirit." -- You receive this one when you are wearing the Darkmoon Covenant Ring and are summoned at the whim of the Dark Sun Gwyndolin.

I received the latter message this time, which I had become used to; it is not the "dark spirit" in the sense of forcibly invading the world of the innocent (or rather, the not guilty), just that you've been summoned by your covenant leader; this apparently also is what Forest Hunters see, and they too are blue phantoms.

So anyway, to my surprise I appeared as a red phantom and thought it was odd, but it must be a glitch, because I didn't use a cracked red eye orb, nor did I use the red sign soapstone. I figured it was just a glitch. Well, yes and no. Yes: it was a glitch; but no: it was not just a glitch of what colour I was; in the game's eyes I had truly invaded as a red phantom. How am I sure of this? Because when the host and their summoned white phantom dispatched me I lost all 150,000 souls and 10 humanity in my possession.

When I respawned in my own world with 0 humanity and 0 souls my jaw hit the floor. That was about three days ago; I got on with it, went back to the Duke's Archives to gain back humanity by lending my summons and went about my business. Put this horrible and unfair glitch (or did I deserve it?) out of my mind.

Fast forward to yesterday, I'm visiting the Giant Blacksmith to make a few upgrades, and when I cross the bridge from his room back to the Chamber of the Princess I decide to rotate my camera and take in the view of Anor Londo. What do I see in the far, far distance: a faint green glow, the one you see hovering over your bloodstain. No, it can't be I thought. I rushed across the main walkway to retrieve it, lo and behold it was indeed my 10 humanity and 150,000 souls. Phew! The best part was that I had completely forgotten about it, but luckily in the interim I hadn't died once. So even though you lose all souls and humanity while invading as a red phantom, a bloodstain appears at the spot you invaded from. This game plays with my emotions, I tell you!

In other news: the Slumbering Dragoncrest Ring (found in Sen's Fortress) rocks. It's pretty much Dark Souls' Thief Ring. I can literally run up behind an enemy up until back-stab range and they don't notice me. If you haven't already, try this ring!

Further updates to come on my Tomb of Giants progress.

Nice job, Pokey. I was unable to best Priscilla on my own; I just couldn't get her invisibility to break.

A note about the Slumbering Dragoncrest Ring: it is like the Thief Ring, but I wouldn't say it's as universally helpful. What it does it mutes all sound coming from you, so walking, running, rolling, whatever, it's all silent. This makes approaches from behind enemies very fool-proof. However, approaching enemies for whom you are in plain sight will not really reduce their "aggro radius" so to speak. If they're slightly turned away it may take longer for them to notice you, but I've found that frontal assaults are pretty much the same with or without the ring.

Just keep that in mind.

Progress update: The Tomb of the Giants is pitch black. I farmed to level up four times to have my Intelligence hit 14 and be able to use the Oolacile sorcery Cast Light, which is invaluable in this place. I retrieved a Skull Lantern, but would rather use the attunement slot for a sorcery than give up my shield to hold a lantern. I was invaded by a member from my former covenant just after finding a bonfire. I actually welcomed this, because apparently Darkmoon Blade invasions knock off a number from your sin level - for some reason I had 1 that I just couldn't get rid of, but now it's gone.

This is a very dangerous area. There are some skeleton dog things that are relentless at eating away your stamina; they must be dispatched quickly and expertly. Luckily later on I was able to summon a phantom to help me with the end of the area, including an NPC phantom invasion from my old pal Leeroy. So sad. Well, anyway we went to take on Gravelord Nito and I think I hit him twice maybe... this person did all the work, because I was too busy fighting skeleton minions ... they were a nightmare for my attempts at targeting the boss.

But now I have a second major boss soul for the Lordvessel. Huzzah. Oh, and I met an old friend down in the Tomb. Still up to his old tricks, too, but he sells a few helpful items as a merchant, so letting him live is a good choice. Anyone who hasn't met this person will know who I speak of when you do!