So I have like 90+ mods installed for Skyrim. I've been repeatedly running into an issue where I can't buy houses. Yes I've done the required quests. I can't even buy Breezehome.

Absolutely none of my mods should even touch the quest needed to buy Breezehome, so I suspect one of the mods I downloaded had something malicious in it. Problem is I can't figure out which one it is short of going through every mod one by one and playing through the starting quests... which is absurdly tedious... Are there any alternatives to find out how this got screwed up? Most players don't notice it likely because most players have already bought many or all of the houses when they start installing mods.

As soon as I figure out which mod it is that's breaking my game I'll let everyone know. But first I need to know how to pinpoint it faster than my current method.

Run those 90+ mods through BOSS and check your quests. If that doesn't fix it, either start a binary search or load your list into TES5Edit to look at the guts of your .esps. Posting your load order may garner more help; someone out there may have had the same issue and recognise a troublemaker.