You may have noticed my players abusing the living hell out of the spell Create Servant. They post them as lead and trailing guards, send them into rooms, make them touch/push/lick things before they touch them, use them to try and open doors.
The wizard has the spell, and he's reasonably good at it. So he can create servants not-too expensively and maintain them for free, in any number he chooses. He's limited more by the "Spells on" rule than by any other constraint. Therefore you see them use and abuse servants constantly.
What are they good for?
They walk ahead and set off traps, spring ambushes, take the first attack, provide inadvertent cover (literal meatshields), and so on. They trail behind and prevent an easy attack on the rear guard by providing a disposable body to block attack. They carry light sources and occasionally drag bodies or tote gear.
It does seem to take a lot of the risk out of exploration. Created Servants are like free hirelings who will listen to any command you give them, attempt anything that isn't inherently combat related, and inspire no need for soul searching when you send them to their deaths. They're as alive as a fireball, and you don't shed a tear when your fireball hits its target and perishes. It's just a manifestation of magic. No one cares if they die, and there is no legal or social cost to getting them killed. It's like people fretting over a bomb-disposal robot getting trashed, if bomb-disposal robots were free of charge.
They're pretty good for all of those uses, too.
But they have some serious drawbacks, too.
What's the downsides?
They're weak. ST 9 is weak. They open the lightest possible dungeon door less than 50% of the time, and an average door never, unless they've got a crowbar and roll a critical success. So unless the door is going to open anyway, without force, they aren't budging it. They can't carry much, either - ST 9 is a BL of 16 pounds, and with Move 4 (they have Speed 4.5 and Move 4) they drop to Move 3 with 16.~ to 32 lbs of gear, Move 2 with up to 48 lbs, and Move 1 with up to 160 lbs (Heavy and Extra-Heavy both drop Move to 1). That's not even an unequipped adult male adventurer in most cases, meaning they need a wheelbarrow, dragging sledge (which is noisy), or another servant to carry a wounded person.
A Brute Servant is more expensive but with ST 16 is a much better deal for carrying things - up to 510 lbs for the same Move. But again, expensive to cast and maintain.
They're clumsy. DX 9 gives a default for most physical skills in the 3-5 range, average 4. So they don't climb well (no roll with a ladder, good thing, because they have skill 4. A rope gives 4 minus 1 = 3 going down, 2 going up). They aren't stealthy. They have Stealth roll of 4, so they can't sneak very well, either. No party with Created Servants ever makes a Stealth roll. They aren't ghosts or light-footed utterly silent Jeeves-Ninjas, they're shuffling magical morons.
They're stupid. IQ 9 isn't bright. It's a little duller than average. That also gives them Per 9, too, and that's pretty bad even with the +10 for In Plain Sight. They default Search to 4, Observation to 4, and have a Per-based Traps roll of 4.
They're weak in the HT department, too, with another 9. Not that it matters - they rarely get hit with anything and not just fold up and disappear according to the rules of the spell.
So they can't accomplish that much.
What about skilled servants?
Yes, some of this is mitigated by skilled servants - you can create them with a skill. One non-IQ non-combat skill at a 16 is good - and Stealth isn't a combat skill. Traps is IQ based, so that's out. You could conceivably give them Search or Observation, though, because they're Per based, but that's a real stretch - Per derives from IQ, so does this fall under an IQ based skill? I'd say yes, otherwise Servants can be given IQ-based chi skills and other oddities. So no Search or Observation, either. Even if they could, they're more expensive - 2 to maintain means you need skill 20 not to pay 1 FP/minute to keep one up. A steady walk down a long dungeon corridor could end in a 50-minute rest as you try to recover from keeping your servant active.
They aren't totally useless, but like Brutes, they come with a cost that's hard to pay over time.
What does this mean as suicidal scouts?
They won't really spot anything. This isn't a problem when you're using them as a suicidal mine detector, setting off traps. It's a problem if you intend to deal with a trap without setting it off, or if the effects aren't limited to killing the servant.
They won't really see anything that's not in plain sight, spot anything hidden, or understand what they see. So they can "scout" in the sense of "go see if anything kills you." They can check for contact traps that don't require a more solid set-off - a hair-trigger trap will nail one, but what about a "fire on door opening" trap?
The way they just disappear if "killed" makes it hard to determine what killed them except via direct observation.
They're vulnerable to No Mana Zones. On the bright side, they detect them automatically. Heh. But so does a Continual Light spell, or even a regular Light spell walked ahead of the party via concentration.
They're not free willed, so they don't make an decisions on their own, making them useful only as a remote drone you have to talk to (loudly, possibly, so they can hear you.)
They are cheap (3/1) but not free, so they do require some effort to put out. And again, spells on - a -1 for each of those servants.
So if you were wondering why I allow all of this with no complaints, it's because I think they're generally using the servants in a way that's fair and consistent with the rules. They lose out a lot - I can think of at least two situations off the top of my head where a servant being used instead of a person cost them some valuable intelligence. They're happy with the upsides, and don't seem to mind the downsides. But it's more "clever play and making a trade you can live with" than "rampant abuse." If it wasn't for the suicidal "go pull that lever" uses, a living hireling (or better yet, actual professional adventurer) could do all of it better and faster. So no, they really aren't a big problem.