Lender counsel (e.g. debt collectors) often argue a guarantor debtor has no defense as they waived all defenses. That is not true. See California Bank and Trust v. Thomas Del Ponti (2014) 232 Cal.App. 4th 162. The court held Civil Code §2856 ONLY waives those defenses specified so defenses such as unclean hands or equitable defenses remain valid. The point is a lender cannot take advantage of its own wrong.