Ovinomancer
No flips for you!
Not disagreeing with any of this in theory, but, again, the results in play may be disappointing in practice. I don't think that you can successfully play a Sherlock character while avoiding situations where INT checks crop up or mitigating a -5 to the point that it's largely irrelevant when they do and still, you know, look like Sherlock Holmes. I'll grant it's theoretically possible and could be very successful, I just don't think it's very likely. Especially since, if I have a player that's expressed an interest in playing a great detective I'm much more likely to include content for that, increasing the chances of necessary checks. I think this is a difference in our general approaches because I don't think you even consider what characters would be at your table in your prep, so having a Sherlock Holmes could be very successfully done merely because that adventure doesn't offer lots of uncertain challenges to the Sherlock character. I don't think this should be relied on in a general discussion of how you might play a Sherlockian PC with a -5 INT.It is funny in that it's a reversal of expectations, but ultimately it wouldn't necessarily be ineffective in actual play. On average over time, a character with a higher Intelligence will obviously do better on Intelligence (Investigation) checks, but that's pretty much irrelevant at the table. I only need to succeed on occasional Intelligence (Investigation) checks, which I'm going to avoid like any other ability check if I can, and if I can't, I'm going to have other PCs working together with me (Watson, perhaps?) or I might spend my Inspiration. If the DM is running the investigation scenario in what I would view as ideal, a failed check is not a dead end but progress combined with a setback which means that my character figures out the thing, but there's a cost or complication which only makes things more interesting anyway.
Again, this isn't a disagreement in thinking so much as a disagreement in how that would actually look at the table. I think it would be disappointing for the player and farcical in practice for quite a number of tables.