What exactly does this ignore?

Will it ignore investigate triggers on attachments at the location?

Will it ignore haunted effects?

What about constant effects on locations?

It's a good card without the other part, but just trying to understand what it ignores specifically related to the location.

Yeah I found it a bit ambiguous as well. I think the biggest boon is Haunted effects. But I’m guessing it would ignore things that alter the investigate check. The Medusa Exhibit in Miskatonic Museum for instance.

The relevant portion of the text is "You may ignore any effect or keyword on your location which would trigger during this investigation." - from this we can determine that the "ignore" effect only works on effects or keywords, and only those that can be triggered (i.e. that have a triggering condition), and only if the triggering condition is met "during this investigation".

It won't affect attachments unless they modify the text of the location itself.

It will definitely ignore Haunted effects since that is a keyword triggered during an investigation.

It won't ignore constant effects unless they have a specific triggering condition that is met during an investigation test.

Examples of effects it will ignore: "Forced - After you successfully investigate this location: Choose and discard a card from your hand."; "Forced - After you fail a skill test while investigating this location" - these effects are definitely triggered (it has the Forced keyword and a triggering condition) during a skill test (per the FAQ, triggered effects that are contingent on success or failure are resolved in step 6 of a skill test). "Forced - after you reveal a [symbol] token while investigating this location: Lose all remaining actions and end your turn." - this effect is likewise a triggered effect that resolves in step 3 of the skill test.

Examples of effects it will not ignore: "This location is investigated with [Willpower] instead of [Intellect]."; "You must spend 1 additional action to investigate this location."; "You cannot investigate this location while you have between 3 and 8 cards in your hand." - these are all constant effects that do not specify triggering conditions and are not triggered during an investigation.

Example of an effect that it probably ignores: "Forced - After you investigate this location, if you did not succeed by at least 2: Lose all remaining actions and immediately end your turn." - this is arguably a more complex version of an effect triggered as a consequence of success or failure and so resolved in step 6, but it could also be argued that the trigger point itself ("After you investigate this location...") is potentially the point after the skill test as a whole. I don't buy that argument but it's ambiguous by the rules as they are.

Example of an effect that it probably does not ignore: "Forced - After you investigate this location, if you are poisoned: Take 1 damage." - this effect definitely triggers after the investigation itself (rather than after determining its success or failure) and therefore is not triggered "during" the investigation. However, that might not be intended - it might be the case that this trigger point is intended to be within the investigation (e.g. during step 8 of the test) and therefore covered by the "during" effect of Read the Signs. Add it to the pile of things that have yet to be covered by the FAQ.

However, since the wording is a bit obtuse, expect any of these conclusions to be overturned by an FAQ entry or developer ruling...