California gives the guarantor the most statutory protection and the most detailed way to give it up. Beyond Civil Code §2856, the sleeper issue is the sham guaranty defense: where the guarantor is in substance the borrower, for instance the sole member of a single purpose entity formed at the lender's request, courts have refused enforcement because it would let the lender evade the anti-deficiency statutes. Structure matters more than labels here.
Texas takes the opposite posture on waivers. In Moayedi v. Interstate 35/Chisam Road, L.P., the Texas Supreme Court held that the fair market value offset under Tex. Prop. Code §51.003 is an affirmative defense, and that a general waiver of every defense surrenders it. The guarantor there lost the benefit of a wide gap between the foreclosure bid and the appraised value. Lenders now add express Chapter 51 waivers, and a Texas signer who skips that clause has agreed to pay a deficiency the collateral would have covered.
New York enforces absolute and unconditional guaranties aggressively. Cooperatieve Centrale Raiffeisen-Boerenleenbank v. Navarro confirmed that such language forecloses defenses the guarantor might otherwise raise, including allegations touching the creditor's own conduct. New York also lets a creditor holding a guaranty of payment move for summary judgment in lieu of complaint under CPLR 3213, compressing a collection action into a motion. Tenants in the city negotiate good guy carve outs because of it.
Florida adds a constitutional twist. The guaranty is enforceable, but the judgment cannot be levied against the guarantor's homestead, protected from forced sale by Article X, Section 4 of the state constitution and subject to the usual acreage limits. Deficiency judgments after foreclosure are also discretionary under Fla. Stat. §702.06. A Florida guarantor is exposed in everything except the house, which is why lenders there ask for extra collateral or a spousal signature. A prenuptial agreement signed before the business existed can matter a great deal in that conversation.