If you are snooping to protect yourself and also that you have boundaries that you WILL enforce if you find something bad out, then by all means snoop away. On the other hand if you are snooping without any recourse planned you are only torturing yourself. Also, if youare in a community property state, any property OR debt is equal property. In the case of a divorce if the debt might be able to be proven his liability due to his drug use. Make sure you keep all detox/rehab records in a safe place that you have access to.
BTW with today's technology snooping is oh-so easy.