Spellcraft in Pathfinder lets you ID magical/cursed items, and the Identify spell adds 10 to your Spellcraft skill. One of my PCs — in this case a level 8 wizard — has a stupidly high INT, making his standard Spellcraft checks up around 24 on a bad roll. I've tried to implement cursed equipment, but he always figures out what it is before anyone can use it.
I could ramp up the DC, but I was wondering if there was another way to handle it?
Make it so that the curse is still tempting. He'll discover the curse, but make the item useful enough that the party will keep it around just in case the curse is worth it.
Requirements or Drawbacks are good ways of doing this. A Sun Blade that causes a constant solar eclipse in a mile radius, a healing wand that moans in pain and requires you wound yourself for 5HP each time you use it, or a staff with a statuette on top that weeps blood and must be washed in holy water to make it work.
You'll want to balance the item's utility and curse so that even knowing the curse the person is tempted to use it, but not make the item so useful that it's automatically worth dealing with the curse. I find that this temptation is stronger if you give your players exact numbers: "Each time you use it roll a d20 and the curse triggers on a 1" is far more tempting than "there's some mysterious chance that the curse triggers whenever you use it."
Items like this will be far more effective if you make it clear that there's no curse compelling them to keep using the item. Something is much more tempting if you can quit at any time. If they need to use remove curse to get rid of the item, most players will immediately reject it.
If the player has invested heavily in this, then it would be a little unfair to just undo all of that by ramping up the DC, so I'd advise against that.
However, there are other options. I'm guessing in Pathfinder it still takes time to identify items. And possibly even money or other resources. This means that the goal might be to not to make something hard to identify, but to reduce the opportunity for it.
Try to introduce something that seems like it would help very much in a situation, but without giving the players the time to sit down and figure out whether it's cursed or not. See how they handle it.
You could also give them a cursed item from a trusted source. Maybe an NPC they trust gives it to them. Maybe he isn't aware of the curse (being tricked by someone else), maybe he's an imposter, but try to present the item as coming from a source that would not need identification.
Cursed magic items are only a minor part of the game in Pathfinder. The PC abilities that are used - Spellcraft and Remove Curse - also have other uses, so don't require cursed items in order to be worthwhile. That means one of your options is to not bother with cursed items at all, if they don't seem worth the effort to you or your players.
The problem you face when including the items is that they are often unpopular. Players will generally have a low tolerance for compulsions with negative consequences applied to their characters by external forces, and will put a high priority on removing them.
This includes non-removable cursed items, but also applies to other things, such as forced alignment changes, Geas, long-term domination etc. Most players I know will tolerate short-term effects, and maybe enjoy them if they provide a chance to to something a bit different, but they will find long-term effects chosen purely by the DM to be unenjoyable.
My suggested fix: Get player buy-in. Make the curse something that the player actually enjoys (even if the PC may not). This might be a compromise on powers (e.g. a sword that is usually +2, but is unreliable and will not hurt some opponents that it "likes" for some reason). But it could also be a compulsion that despite being a curse when viewed in-character, that the player enjoys to roleplay, such as a Bardic instrument that forces the PC to speak in rhyme.
In a similar vein, quite a few players enjoy the traditional fantasy curse of lycanthropy, for the heady combination of roleplay opportunities and additional PC power, even if temporary or difficult to control.
Hopefully you know your players well enough to know if a mechanical trade (more power for unreliable effects) or an open-ended story hook is what will tempt your players to view cursed items as opportunities, in a "deal with the Devil" kind of way, and not DM power over their character.
How about maybe culturally cursing the items... By this I mean that the items are as identified magically speaking, however, using them, wearing them, or people seeing them will cause you 'issues'.
I'm thinking of things like: 1. Class Status: Only lower class people wear/use said item, therefore you must be lower class (sort of like the Indian Untouchable caste)
Taboos: Using said item violates a taboo in the area
Similar/Same as hated group: For this I was thinking of something like -- only the local evil, murderous cult uses/wears said items, so since you have it/them you must be one of them (and/or be able to talk real fast...) or that looks like an item from a rival city/ruler/clan/etc and so...
What I'm suggesting here is 'curses' that Identify and Remove Curse wouldn't affect (and your uber powerful Mage couldn't readial see), but, would create Roleplaying moments... Like, why you were tossed out of the high classed inn you entered and the only inn you could find would be outclassed by a hovel. Or, why the villagers are looking at you with evil eyes, spitting , and making warding signs as you pass and the merchants are either trying to fleece you, giving you pittances, or generally trying to hustle you out of their store Or, the guard is really, really interested in you and taking an inordinate interest in you -- more so than they should...or when they pop up at your inn at 3 am and want to have a nice, 'friendly' chat about the most recent murder/theft/crime...
