First, I am using this reply (without any quotes of the article to which I am replying) since the page for that type of reply comes up unavailable--for unknown reasons.
Anyway, clicks and pops are not "noise" in the sense that this word is used in Wavepad. Rather, noise refers to background hiss, such as present in various types of recording media. In other words, an attempt to use the WavePad noise reduction "effect" will not succeed in removing clicks and pops. Furthermore, I have found that the clicks and pops which I am regularly fighting are of very short durations, such as just a few milliseconds. It is amazing how sensitive the ear is to a short-duration spike in the sound wave. When I really want to clean up a clicky and poppy waveform, I laboriously spend a lot of time going throuh it and _manually_ removing those clicks and pops.
Another technique that you are undoubtedly unaware of is to press the space bar while you are scrolling through an audio waveform. When you do this, the scrolling will stop and there will be annoying buzzing sound, along with the highlighting of a small portion of the waveform surrounding the current selection point. But I do not use this preselected portion (given to me by WavePad). Rather, after I have stopped the scrolling, if I want to work on the area surrounding the selection point, I press ESC, which stops the scrolling and the buzzing. Then I select a small portion of my own near the selection point, followed by the keypress CTRL-SHIFT-S, which causes the selected portion of the waveform to fill the screen, exposing that nasty little click/pop devil. I then select the devil and delete it. However, the time scale has been drastically increased by zooming into the full screen. Hence you will now have to compress it by zooming out with a series of CTRL - presses to get back to where you were before. You may then restart the play with F9 and continue from there, etc.
The big advantage of using this technique is that a toggling of the space bar will alternately start and stop the scrolling very conveniently. The most effective way by far to get a handle on these clicks and pops is to LISTEN carefully while you scroll the waveform. When you hear the telltale click or pop, press the spacebar, which stops the scrolling and gives you the buzzing. If you decide that you do not want to attack the particular little devil that caused the click or pop which you heard, simply press the spacebar again and the scrolling will resume, etc. You see, it is practically impossible to tell _by looking at the waveform_, which spikes or imperfections will be audibly objectionable. Depending upon the particular time scale being used at the time, what looks like a horrible spike may not be heard. Try closing your eyes as you scroll through the file using this spacebar toggling, and quickly press the spacebar when you hear that telltale click/pop. Try to use earphones while you do this. If you look at the wave form while you are doing this, you will be misled as to the significance of some particular spike in the waveform.
As to the spectral noise thing, this is an excellent noise-reduction method; just remember that "noise" is not clicks and pops. Simply select a portion of the waveform containing _noise only_; that is, in between tracks or perhaps at the beginning or the end. Then "grab" this sample, deselect the portion containing the grabbed noise sample and use the spectral noise reduction. What this does is to subtract the portion of the spectrum that contains the noise--hopefully at a frequency band largely outside the music. Give it a try.
That's about it for now. This particular technique is very easy to use, in contrast with click/pop reduction or elimination in general. The other form of noise reduction is much less effective and, at least for me, usually chops out too much of the music at the high-frequency end. So I avoid using it. But then, that is my own personal preference. It may not be yours.