"Penetrated perforations" may refer to a characteristic of some German inflation stamps that is mentioned in the Michel Deutschland-Katalog:
"Der sägezahnartige Durchstich verschiedener Inflationsausgaben ist so mangelhaft, dass für ganz fehlerlosen Durchstich ein Preisaufschlag gerechtfertigt ist." (The sawtooth-like rouletting of various inflation issues is so defective that a price increase is justified for completely error-free rouletting.)
But note: "Der bei einzelnen Werten angewandte sägezahnartige Durchstich ist als Nebenart anzusehen, da die Haupttrennungsart stets die Zähnung war." (The sawtooth-like rouletting employed for some denominations is to be regarded as a variant, since the main type of separation was always perforation.)
Here's an example of defective rouletting on a German Infla-Marke, from the
German Wikipedia article on postage stamp separation:

Since cehicks20's stamp is actually perforated rather than rouletted, the distinction between well and poorly rouletted stamps would not apply.