contracts written for one spouse but signed by the other

Most likely it is binding.  Contracts are valid when entered into by an authorized agent.  The wife was likely authorized by the husband to enter into the contract for him.  Even if the wife did not have ACTUAL authority, the contract would still  be valid if she had either IMPLIED authority or APPARENT authority.  Implied authority comes about in a situation where an agent holds a position where one would expect them to have authority, and the principal doesn't notify people with whom the agent deals about any limit on the agent's authority.  For example, the president of a corporation would normally be authorized to enter into a lease on the corporation's behalf, so if he/she did so, even if the corporation's board of directors had expressly told him that he could not, the lease would be valid (although the president would be liable to the corporation for the breach of his authority), unless the landlord knew the president didn't have authority.  Here, the argument would be (and there may well be case law on this but I'm not familiar with Virginia law), a spouse normally has authority to act on the other spouse's behalf, so the wife had implied authority to sign the contract.  Apparent authority is where the principal puts the agent in a position where third parties would assume the agent had authority.  For example, if a store owner asks a friend to watch the register for her while she mails a letter, customers would naturally assume that the friend had the normal authority a cashier would.  Here, the argument would be that the husband evidently allowed his wife to be in a position to sign the contract (without knowing the details I can't say exactly how.)  Also, even if the contract was void initially, if the husband learned that his wife had signed the contract and went along with it, he would have ratified the contract so that it became valid and enforceable.