Allowing this to happen is always a bad idea, but your risk will vary by document/product/regulation.
If you're talking about the promises made in contracts (including notes and service agreements of all kinds), state law (especially case law) will prevail. Having no signature or a forged signature does not matter UNTIL you have to go to court and sue the customer for nonperformance of one or more of those contractual obligations. With the chips down, count on the non-signing spouse to argue "I never signed that and can't be held to those terms." If you can't prove that, in fact, s/he DID "agree" (by signature,"X", or electronic "X"), you lose. If you have reason to suspect the objecting spouse's signature was forged (manually or electronically), you will lose AND the judge will probably chastise you for wasting the court's time with a claim based on a forged signature.
If the signature (manual or electronic) is obtained to acknowledge receipt of documents, then your risk stems from the law, regulation, rule, contract, or whatever required you to deliver the documents in the first place. If the law/reg/rule specifically required you to obtain a signed receipt, then failure to prove you have a valid signature exposes you to whatever penalties specified for violations of that particular provision. If there's no requirement to obtain a receipt, but you want one anyway, then your exposure is indirect for unsigned or forged receipts. Customer says "I didn't get it." You say "we gave it to you." Court, regulator, investor, etc. will need additional evidence in order to side with the big, bad bank. If a forged signature is your whole game plan, the customer didn't receive the document and appropriate penalties will apply.