And have refused to in the past for various reasons. But when I need to, I start a conversation with them, what kind of diving they like to do, how often, what trips they've been on and to where. Were they satisfied and if not, why? When we exchange info like this in a conversation, rather than questioning them like an interrogation, I learn what they expect out of a dive, what their experience level is, how comfortable they are before the dive. If we're at a resort, I'll know if they like to party, were maybe up late the night before drinking. I pay attention to how they pay attention to the DM during the dive briefing, how do they treat the crew and other divers. At the same time I'm looking at their gear. Is it in good condition, is it decent quality or is it discount brands sold by cheezy on-line suppliers. Not to be a snob, but if they only buy cheap gear, where else have they tried to cut corners...their training, perhaps? If we both feel comfortable with each other, we'll explain our gear and how it works. For instance, I use an Octo+. I explain if he/she needs air, I'll give them my primary.
Bottom line, if I don't feel comfortable with this person, I do not dive with them and am glad to tell them why. And anytime a DM or boat crew tries to force me or quilt me into diving with someone, I don't do it. The safety of me, myself and I are my first priority and I don't entrust any of the 3 to someone without a great deal of thought.
