As a general principle, from a DMs perspective, I like racoon traps:
You line a knot hole with spikes (nails) and the 'coon reaches in to get the shiny bit you've left at the bottom. Now, it can't get its paw back out. If it lets go of the shiny bit, it can go about its way with some minor scratches, but it wont, so it stays stuck.
The same principle applies with PCs: Imagine a ten-foot-deep, spiked pit trap. At the bottom, besides the spikes, are a long-clean humanoid skeleton, a faintly-glowing longsword with a jeweled pommel and some kind of inscription on the blade, a few hundred coins of various mints and denominations, and an iron staff with a large jewel attached to the visible end.
Anyone entering the pit is trapped there by a wall of force, and they discover that the pit is inhabited by a vicious otyugh. The sword is just a display piece, the staff is a prop and most, but not all of the coins are copper. The otyugh's sticky hide though, bears some small bits of jewelry, and during the fight, it seems to be defending the tunnel from whence it came. Further investigation of this tunnel (hopefully, after the wall of force expires) leads to a wounded dragon with a less-than-average hoard. . .
This cycle goes on, taking more resources from the party than it rewards them. They could retreat from this path of red herrings at any time, but they invariably hope that the next treasure will be the big one.