Back in 2008 or so I used to do a ton of IDOCs with my guild on Great Lakes. Only two of them really stood out, the rest were just standing around, waiting to pick **** up.
The first was a keep in the middle of a Trammel swamp. There were surprisingly very few people who showed up but those who did had swamp spawn lured on them. A few people said that they paged on us but no GM ever came. The keep was loaded. Probably the most profitable of any IDOC I have ever done. We also managed to place a new guild house in the spot.
The second was a Fel keep. It probably had as much or more stuff as the first one, but there were 3 reds there that were guarding the loot fairly well. None of our guild had PvPed a day in their life, not to mention had any sort of template set up for it, but we outnumbered them 2 to one so we thought it would be a fairly even match. We were so very wrong, so we backed off and called in a favor from our alliance which consisted of this one dude and his two daughters. The dude had a red macer so we figured he could fight but I think his template was incredibly old and even 3 to one we didn't stand a chance. Most of the guild gave up after that but a few of us got on stealthers and picked at the loot while being chased by these guys. We got a few good pieces out of it I think, but it was probably the most fun I ever had playing UO.