xxx xxx xxx Q Is Lorna Guevarra alone in her succeeding return trips to your house at San Andres, Sto. Domingo, Albay? A She was with Josie Bea sir. xxx xxx xxx Q Did you know as to how much did they demand for the favor they are extending to you? A P30,000.00 sir.xlii[42] As can be seen from the testimonies of the witnesses, the accused-appellants committed acts of recruitment such as promises of profitable employment to complainants and acceptance of placement fees. Such acts fall squarely within the definition of recruitment and placement under the Labor Code. With the certification from the Department of Labor and Employment stating that appellants were not authorized to recruit workers for overseas employment, it is clear that the offense committed against the five complainants is illegal recruitment in large scale.xliii[43] The accused-appellants asserted that the offense should not have been qualified into illegal recruitment by a syndicate since there was no proof that they acted in conspiracy with one another. However, the acts of accused-appellants showed unity of purpose. Guevarra would visit each of the complainants in their houses for several times, convincing them to work abroad, and giving them the impression that she had the capability of sending them abroad. She would accompany them to the house of the spouses Bea, who, in turn, would collect the placement fees and process the passports and plane tickets. All these acts of the appellants established a common criminal design mutually deliberated upon and accomplished through coordinated moves. As against the evidence built by the prosecution, the accused-appellants merely raised the defense of denial. However, denials, if unsubstantiated by clear and convincing evidence, are deemed negative and self-serving evidence unworthy of credence. They have no evidentiary value when ranged against the testimonies of credible witnesses on affirmative matters.xliv[44] The credibility of witnesses is best left to the judgment of the trial judge whose findings are generally not disturbed on appeal, absent any showing that substantial errors were committed or that determinative facts were overlooked which, if appreciated, would call for a different conclusion.xlv[45] The trial court has the advantage, not available to appellate courts, of observing the deportment of witnesses and their manner of testifying during the trial. Thus, appellate courts accord high respect to the findings and conclusions of lower courts.xlvi[46]