While it is certainly possible to use a low HD humanoid and challenge players, the specific problem I've always had with 'Tucker's Kobold's' type situations is that almost invariably they end up resolving to 'the DM judges the kobolds by different standards than he would judge the players'. Invariably, in 1st edition and 2nd edition desciptions of 'Tucker's Kobold's' type challenges, there are always special rules created to give the kobolds some advantage.
And even when there aren't, the kobolds still have less tangible but certainly important advantages that are the result of being run by the DM. For example, 'Tucker's Kobolds' never have command and control problems. They always know where the PC's are and are always able to perfectly coordinate their actions. They never waste time or delay anything else because they are never short of information. Not only do they act as if they were part of a telepathic hive mind, but they effectively have omniscence.
Likewise, any 'off stage' kobold more or less has the ability to teleport once it gets more than a round or two from the players. They never fail to be able to perfectly predict the player's actions and move without fail to cut off the players. They are always able to swarm to the player's positions whenever any kobolds remain alive. They are always on hand whenever they need to be.
Additionally, they have perfect knowledge of the player's capabilities. They know exactly what to prepare for. Whenever they are on hand, they always have exactly the right tools prepared to counter the PC's plans.
Additionally, they have infinite resources to make those preperations. They can purchase or make any counter they desire, and if these defenses are trashed they have an infinite amount of labor and raw materials to repair the damage.
The sort of DM's that got off on 'Tucker's Kobolds' scenarios seem particularly prone to this sort of thing, often without even being consciously aware that they are doing it. It's even shown up in published scenarios. For example, the goblins in 'Axe of the Dwarvish Lords' basically had all the above problems in spades, and the 'special rules' they used for mass archer fire, opening doors, and so forth were simply DM cheating because the same things would never be allowed for low level PC's.
Still, it's not hard to come up with scenarios where the HD of the monster has little or no impact on the threat posed by the attack.
1) Ranged touch attacks: Ranged attacks are good in general, because they neutralize a certain portion of the PC's attacks. At sufficient range, the throw a PC needs to hit approaches 20, which turns missile exchanges in to a shear battle of numbers. Ranged touch attacks are even better, because they neutralize a good portion of the PC's #1 advantage - superior armor class. If you add to that grenade like weapons, so that there is a good chance you'll 'hit' even if you miss, you get into a situation where it doesn't matter what the THAC0 of the attacker is all that much. Burning oil is the perfect weapon for low HD monsters.
Never mind that a typical 'Tucker's Kobold' tribe will in a single session burn oil worth several times the total value of goods that a kobold tribe is supposed to own, and never mind that whatever the source is of all this wealth it probably won't be made available to the PC's no matter what.
2) Poison: Poison is another big neutralizer, because it neutralizes another one of the PC's biggest advantages - superior hit points. Each hit becomes threatening, regardless of the PC's remaining hit points and potentially vast healing resources.
3) Ballistic Weapons: If I'm blindly lobbing ordinance over an opaque wall, it basically doesn't matter that I don't have particularly good aim. The chances that I hit are entirely based on luck at that point, and in all likelihood any return fire you make will be similarly handicapped. Moreover, since most spells rely on line of sight, I've just neutralized another one of the PC's biggest advantages.
4) Highly Favorable Terrain: I have 90% cover, am located 20' up a wall on the other side of a concealed pit, and you are fighting on an uneven stone floor covered with hot pig fat and liberally sprinkled with caltrops. Additionally, I've strung lengths of sharpened piano wire about the room at various heights.
5) Abusing 'tame' monsters: So, I just threw a nest of hornets into the middle of the room. Swarms are great. And, I'm not just lobbing rocks over the wall, I'm lobbing clay pots containing green slime/yellow mold/rot grubs. And, the concealed pit contains a black pudding. And the tribe has well trained giant weasels/hell hounds they can unleash for their kennels.
6) Traps: Naturally, a whole tribe of kobolds manages to safely live in quarters that are more lethally trapped than Acerak's tomb without ever having accidents.
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