Distorting Lettering in Photoshop
For this tutorial I'll use the same starting image as the transparent text version. Firstly create a new layer in photoshop and type in the text you require. Then when you are happy with the font and lettering size, create a new layer above the lettering layer.
Now select the Airbrush tool from the tools menu and choose a colour from the swatches panel. For this tutorial I'm just going to choose the colour white.
I have chosen a selection of brushes from the Photoshop Brushes page, and on the new layer I have sprayed white over the original text, using a brush pressure of 50. You can alter the opacity of the sprayed layer to make the white spray lighter, or another trick is use the eraser tool (and a grunge brush) to remove sections of the white on the sprayed layer.
The image on the left shows the S from the first layer on an opacity of 50, you can see how it has faded down. I have also quickly added another new layer and continued to spray building up the white over the letter P.