Re: It thick it's a simple question; why can I never get an answer?
Well, I can't say for certain it gets into your lungs, but it does irritate your airway. PND can cause a chronic cough because it "tickles" the airway. So knowing that, I would say yes it does enter atleast the airway.
There are many reasons why someone is unable to cough up mucus. First being the inablility to produce an effective cough, but by your post that doesn't sound like that is the issue. If the mucus is thick it is harder to become mobile. It is good to stay hydrated but in some cases like chronic bronchitis if you become over hydrated it can cause the mucus to "swell" up causing more of a problem.
There are different coughing techniques out there and one used most often is the huff cough. Breath in deeply through your nose and out through your mouth a couple of times. After you breathed in deeply do a cough that resembles you saying "HUFF" "HUFF" "HUFF". It has been shown to cause increased vibrations and help mobilize mucus. The huff, huff, huff should be done with one exhalation with 3-4 huffs a few times. The huffs should be forceful but not "barking".
Another technique is quite often used with cystic fibrosis, it's called autogenic breathing. It is a series of breathing, diaphragm breathing, coughing that has been shown to be VERY effective at removing secretions. It is used quite often over seas but unfortunately it is often time consuming and the US doesn't use it as much. Go figure right.... I know you didnt say you had cystic fibrosis, but if you do a little research on autogenic breathing on the net you might find some techniques that may help you up getting that mucus up.
Also, there is a device called a flutter valve or acapella that causes vibrations in the lungs when you exhale. They are fairly inexpensive and have shown to help a lot getting those secretions mobile.
Definately talk to your doctor as he/she may be able to get one prescribed for you, if not, they are very inexpensive.
Hope this helps.