Can one make a bracha on shaking an esrog left under a bed which a person sleeps on? (Yoreh Deah 116:5 says liquids and cooked foods placed under beds get ruach ra attached to them.)
Ayin Yitzchak 24:9 - Rabbi Yitzchok Elchonon Spector says one may use such an Esrog for the Mitzva.
The Kaf Hachaim 649:80 writes tzarich iyun if one can make a beracha on such an esrog.
Rav Elyashiv(sefer Ashrei Haish pg 218) holds that one can make a bracha on such an esrog.
Rav Shmuel Kamentsky in Kovetz Halchos pg 312 holds that one can make a bracha,he brings a proof from the Pischei Tshuvah 4-5,and also the Sdei Chemed.
The Rivevos Epharaim 4:153:25 brings from Rav Yoel Schwartz that it depends on the machlokes of food found under bed,the Gra is machmir so it would not be good eat,but according to the other poskim it would be mutar(bdeved) for the mitzvah.
The Steipler Gaon holds one should not make a bracha on such an esrog,the Chazon Ish held one does make a bracha on such an esrog (Arbah Minim l'mehadrin)