My league includes teams with dead cap ranging from $4 million to $44 million. Is dead cap any indicator of the health of a franchise?

No. Just bad contracts. Without knowing details. Several things could have happened. Good and or bad. Previous owner cutting bad contracts to set up a good cap situation next season. Owner trading away players with large bonuses that accelerate cap hit just to name two.

Another common occurrence is an owner not renewing for another season, then the Ai takes over and signs an aging vet to a long term deal with a big bonus. When that vet retires 1 day later, the team (and new owner) are on the hook for the signing bonus.

$44M could come from only one of those deals.

Also busting first and especalliy second round Talent with 4 years on the rookiecontracts. Cutting them after the TC will add Dead Money in the Range of about +6 Mill. depending on the round there drafted