Glue will soak more into the end grain of wood and can potentially result in starved glue joints. To help prevent this, you can "size" any end grain to be glued with a mixture of glue diluted with water. Dilute just so that when it is applied, glue drops don't form at the lower edges of the wood. Another method, somewhat less effective, is to coat the end grain with full-strength glue, allow it to dry 5 to 10 minutes, then re-coat with glue and assemble.
Dirty woodstove glass? Try dipping a dampened piece of newsprint in the fine white ashes after your fire has died. Whipe it onto the glass in circular motions – it works well if the glass isn’t terribly dirty to begin with.