Originally Posted by gsa103

Not really. Rotate the wheel so the valve stem is at the bottom, let the air out and remove the valve stem. You can then stick a zip tie into the bottom of the tire and use it like a dip-stick. The tire beads will typically remain seated, so its easy to re-inflate.

If the sealant is dry, simply pour more in with the valve core removed.

Save yourself some effort and don't bother cleaning out the gooey mess inside tires. It doesn't really effect anyting, and most people agree its not worth the effort.