Rabbi Vaye explains it is difficult to distinguish them because of the build of a pepper, hence he recommends removing the stem with the top of the pepper and then to cut lengthwise or widthwise, soak in water with a little detergent for about two minutes and rinse inside and out.
This phenomenon is not dependent on any specific season of the year.
Additional information with accompanying photos may be found in his book, Bedikas Mazon K’Halacha.
Click on the hyperlink to the side to read Rabbi Vaye’s alert in the original Hebrew. נגיעות בפלפלים לעיתון