I use them from time to time, though I discovered that in 3.5e, at high levels, they can become PITA to run.
For one D&D game, none of the PCs was a rogue, and they wanted to recruit someone to handle traps. So, I sketched out several would-be adventurers, and let them do interviews, and decide which one to take. I included an obnoxious guy, some young wannabes (that were clearly 1st or 2nd level -- much lower than the PCs, who were around 8th level, IIRC), a hulking half-orc whom they'd previously talked to when looking for muscle*, a sly type that would've eventually tried to double-cross them, and a surly dwarven trapfinder that demanded a full share & had a list of things she didn't do ("Undead, constructs, cooking").
*Approximate transcript of interview:
[sblock]PC1: "I though this guy was a barbarian?"
PC2: "Krusk, how would you deal with a crossbow trap?"
NPC: "KRUSK SMASH!"
PC2: "How about a glyph of warding?"
NPC: "KRUSK SMASH."
PC1: "Right, barbarian."
NPC: "Krusk also cook good. Krusk have many hidden facets."
Really, I was rooting for them to hire Krusk.[/sblock]
(Edit: to answer the comment, they went with the surly dwarf; I think they finally judged her the most competent traphandler they could trust. Krusk was sorely tempting, though, for at least a few of the players.
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