May one sit by the corner of a table-and does it affect your chances of getting married?
Many of the populace are accustomed for single men and women not to sit by the corner of a table as doing so prevents one from finding a Zivug. There is no known source for this custom in any Jewish literature, and it certainly does not derive from the Talmud or Poskim.
The Halachic debate: Some Poskim would negate the above practice, claiming that doing so transgresses Darkei Emori being that it has no logical reason or source behind it, and therefore one is to avoid doing so. Likewise, it may transgress Lo Sinacheish. However, other Poskim would rule that its practice does not involve Darkei Emori. Furthermore, some Poskim rule that it is permitted and even praiseworthy for one to believe in superstitions that the general populace believes in even if it has no source in Sefarim and the words of our sages, as the prohibition of Lo Sinachesh only applies when one verbalizes the superstition.
Practical ruling: This adherence is not an established Chabad custom, and many amongst Anash are not particular in it. Accordingly, one who does not have such a tradition should not adapt it due to the above Halachic issues surrounding it. Nonetheless, those who received such a tradition may continue doing so.
 Custom brought in Darashta Vechakarta 5:22; See Segulas Rabboseinu p. 223-7 that Rav Chaim Kanievsky replied that he is unaware of any source for this
 See Darashta Vechakarta ibid for an explanation of this custom based on Divrei Torah 1:7
 See Rama Y.D. 177:1; Admur 301:33; Mishneh Shabbos 67a; See Rama Y.D. 178:1 “This is only forbidden if the clothing of the gentiles are worn by them for sake of frivolity [pritzus] or it is a gentile custom that has no logic behind it, as in such a case there is room to suspect that the custom derives from the Emorite customs, and that it derive from practices of idolatry passed down from their forefathers.”; Maharik 88; See Kapos Temarim Yuma 831 and Chavos Yair 234 that Darkei Emori applies towards practices that the gentiles developed as a result of idolatry, that they believed that these actions invoke their G-ds to give assistance. See also Ran on Shabbos 67a; See Admur 301:33 “Any medical treatment that works in accordance to Segulah [i.e. supernatural causes] rather than natural cause and effect [i.e. scientifically based] does not contain the prohibition of Darkei Emori so long as it is recognizable [to the onlookers] that it’s intent is for the sake of healing”; See Igros Moshe E.H. 2:13; Y.D. 4:11-4; O.C. 5:11-4; See Mishneh Halachos 12:137 “This is not a Jewish custom, and is certainly not a custom of meticulous Jews [i.e. Vasikin]…to recite ”Bless you” after a sneeze we have heard of, however what does this have to do with pulling at the ear, and one should not do so due to it being the ways of the gentiles”
 See Hagahos Maimanis Avoda Zara 11:1 in name of Yireim 313; Beis Yosef Y.D. 178; Sheiris Yaakov 12; Darkei Teshuvah Y.D. 179:30; Rashba 1:167; 825; 2:281; Halef Lecha Shlomo Y.D. 115; Talumos Leiv 3:57-3
 Shiltei Hagiborim Avoda Zara 9a, brought in Pischeiy Teshuvah 179:3; See Yerushalmi Terumos 8:3 that one needs to suspect for that which people worry of danger; Sefer Chassidim 261 that there is danger involved in matters that people believe to be dangerous; Minchas Yitzchak 9:8
 Heard from Harav Eliyahu Landa Shlita that he has not witnessed this Minhag by his family or amongst Anash