a bad gif

Judith Mossman undergoing transformation from LOD values 0 through 6. LOD value 6 is the absolute lowest polygon version source will allow models to be rendered in on the default directx9 version of the game. By default all models in source games will be assigned higher and higher LOD values as they become farther away. 

If you would prefer that everything always appear in its LOD 0 value (the highest fidelity one), you can simply type r_lod -7 in console after enabling cheats. Inversely if you want to force the lowest quality model to appear type in r_lod 6.