"God deliver me from sour-faced saints".

François Gérard (1827)

"Dios me libre de santos encapotados".

     Letters of Saint Teresa:  a complete edition translated from the Spanish and annotated by the Benedictines of Stanbrook; with an introd. by Cardinal Gasquet, vol. 3 (London:  T. Baker, 1922), 295n2.
     More critically, "Virtudes de nuestra Madre Santa Teresa segun una relacion de su prima La Venerable Madre Maria de San Jeronimo," Appendix LV in Obras de Sta. Teresa de Jesus, ed. P. Silverio de Santa Teresa, C.D., Biblioteca Mistica Carmelitana, vol. 2, Relaciones espirituales (Burgos:  El Monte Carmelo, 1915)), 301 (291-302).
     Moreover, the plural occurs in the Introduccion to vol. 5:  "Dios nos libre de santos encapotados" ("God deliver us from sour-faced saints"; Obras de Sta. Teresa de Jesus, ed. P. Silverio de Santa Teresa, C.D., Biblioteca Mistica Carmelitana, vol. 5, Las Fundaciones (Burgos:  El Monte Carmelo, 1918)), x).
     According to Dr. Eric W. Vogt, Professor of Spanish at Seattle Pacific University and translator of The complete poetry of St. Teresa of Avila:  a bilingual edition, 1st ed. (New Orleans:  University Press of the South, 1996), 2nd ed. (2015), "This is a hallmark sentiment of hers. She expresses it frequently, consistently and many ways in her writings, including in her poetry" (note to me dated 31 December 2015).
     encapotados:  scowling, frowning, cloudy, lowering (and presumably sullen).  (But I haven't checked a period-specific dictionary such as one of those included in the Nuevo Tesoro Lexicográfico de la Lengua Española.)