Okay uhm, let me say this, if you leave the bottle uncapped that's not going to dry the glue, you can leave the skrewing part of the lid unskrewed and air still hits the glue and it doesn't dry. No matter what, glue does not dry inside of the bottle because of the adhesives in the plastic that keeps it liquified. So until the glue comes in contact with something else other than other liquids and the inside of the bottle, it has no chance of drying.

More importantly, why doesn't hydrochloric acid eat through the bottle?

It would and does if it has a chance to dry...thus, the lid.

Jed makes an excellent point. Even if you don't take the cap off, though, the glue DOES tend to stick to the inside of the bottle. However, the glue that doesn't come in contact to the sides is the stuff that comes out.

Jed-That's odd, I never knew that it would stick if you left the bottle uncapped. Thanks for the warning :-)

It would if you left the cap off the bottle.