Symptom feigning and malingering should be evaluated in forensic contexts due to their important socio-economic consequences. Despite this, to date, there is little research in Spain that evaluates its prevalence. The aim of this study was to investigate this issue using the perception of the general population, students, and professionals of medicine and forensic psychology. Three adapted questionnaires were applied to a total of 1003 participants (61.5% women) from 5 different groups. Approximately two-thirds of participants reported knowing someone who feigned symptoms, and one-third disclosed feigning symptoms themselves in the past. Headache/migraine, neck pain, and anxious–depressive symptoms were the most commonly chosen. Experts in psychology and forensic medicine estimated a prevalence of 20 to 40% of non-credible symptom presentations in their work settings and reported not having sufficient means to assess the distorted presentation of symptoms with certainty. Professionals and laypersons alike acknowledge that non-credible symptom presentations (like feigning or malingering) are relevant in Spain and occur at a non-trivial rate, which compares with estimates in other parts of the world.