Both of Polly’s husbands were her first cousins.

1850 census of Tazewell Co., Virginia, western district, enumerated 31 July, lists on p. 61 as family #401:
Jno C. Baily, 39; Polly, 44; Estill, 13; Granville, 13; Carmack, 12; Biddle, 10; Edwin, 9; Festus, 8; Clinton, 6; Mary F., 4; Nancy J., 4; Catherine Wemer, 24. All born in Virginia.

The next household is that of John’s mother Nancy and his two brothers Jonathan and Harvey.

1860 census of Tazewell Co., Virginia, eastern district, Bluestone P.O., enumerated 13 June, lists on p. 22 as family #142:
John C. Bailey, 49, farmer; Polly, 55; Carmack, 22; Biddle, 20; Edwin, 19; Festis, 17; Clinton, 15; Nancy J. M., 13; Mary F., 13; Sarah A. V., 9. All born in Virginia.

The preceding household is that of John’s brother Harvey.

1870 census of Tazewell Co., Virginia, Clear Fork township, Bluestone P.O., enumerated 11 Aug, lists on p. 35 as family #225:
Bailey, John C., 59, farmer; Polly, 54; Festus, 27; Nancy, 24; Sarah A., 20; Jonas John, 18; Caffey, Charles, 17; Patsy, 35. All born in Virginia.

Two households above at #223 is the family of Harvey G. Bailey, with John’s mother Nancy.

1880 census of Tazewell Co., Virginia, Clear Fork township, E.D. 87, enumerated 15 June, lists on pp. 34-35 as family #274:
Bailey, John C., 69, farmer; Polly, 74, wife; Carmack, 42, son, farmer; Sarah A., 29, dau; Alen, Visa (f), 46, servant; Leander S., 11, son. All born Va Va Va.

The John C. Bailey family is no longer adjacent to the Harvey G. Bailey family, as they were in 1850 through 1870. The reason I mentioned the enumeration district is that it is coincidence that the two households were both on page 34 and at similar numbers, because they were in different districts.