Not much. end up as a knarly mess om the ground. Half runners have stiff enough vines to hold up and produce.Have to lift up the vines to harvest tho.

Some pole beans, when not given support, start to send up runners and then abort them. As Farmerdill has stated, it's a mess. If you have some planted without support, consider setting some poles for them. As long as they are still growing, you can probably get them to start climbing.

I've had a few things happen:

-some beans, particularly southwestern varieties and the weaker climbers, seem happy just to sprawl across the ground.

-very strong climbers, such as Blue Shackamaxon, climb up each other in a crazy tornado/tipi shape that self-supports 3' tall plus before getting floppy

-as others have mentioned, a tangled unproductive mess on the ground, that also wraps itself around anything in its path and tries to climb it (strangled a tomato pretty good that way)

I'm pretty sure I've read that commercial bean growers in my state (CA) grow their dry pole beans with no supports, since at that scale the loss in plant productivity is worth saving the human labor in setting and taking down thousands of poles. Though I suspect that only works well in drier climates where soil contact isn't as conducive to rot. Generally in the garden pole beans are most productive and happy when given any poles at all. When things've gotten away from me a bit sticking poles into the tangly mess does help; the beans climb up them straight away and produce better, even if it's not the tidiest-looking.