If such an inheritance goes towards buying a house your spouse lived in too, you might lose that house. You comingled the funds.
Example:
House is $100,000
Used $50,000 of inheritance to pay for it
$50,000 of marital funds to pay for it
When divorce you receive $75,000 and the other party receives $25,000
If you bought a boat with it that both of you used, you might lose the boat. If you bought a car that both of you drove, you might lose the car.
It doesn't matter who uses the asset, the origin of the asset is what matters (with what funds was it paid for with). Cars would work similar to the house. Any marital funds used towards the non-marital originated asset would take a portion out of the asset.
example:
Receive $100,000 boat (value) as inheritence with $20,000 lein
Use marital funds to pay off the lien on the boat.
At divorce you receive $90,000 while the other party receives $10,000
(Maintenance costs are another issue that I won't get into at this time as that would change amounts, but likely not significantly)
So functionally, it helps very little unless those funds are sitting in a non-joint account and never really used for anything. Alternately, you could track every cent you spend...
It's pretty easy to trace amounts that are worth tracing (5 figures or greater). They tend not to just disappear as there are receipts kept by financial institutions regarding those transactions.
Which begs the question, 'why'd you get married in the first place?'
Not really relevant. People have different reasons for marriage. Many reasons are financial.
The vast majority of married people aren't keeping separate accounts, and a second set of books in case of divorce.
Separate accounts don't matter. Even with separate accounts any amount earned by each party is considered marital. You don't need a 2nd set of books. Regular accounting can easily show where things go.
Not spreading FUD. I do this for a living. It's more simple than people lead on unless you happen to be the type of person that pays cash for everything.