Purpose This study conducted a survey of Mexican millennials to measure the extent of negative bias and perceived advertising value they experienced towards the ads they encountered while performing search for local products and services from their smartphones. Design/methodology/approach Using a paper survey with a scenario question, responses were collected from 1215 Millennial smartphone owners about the strategies they used for scanning mobile search organic and sponsored results and quickly reaching the information they needed when performing mobile search. The 315 participants who reported clicking on ads were further surveyed on their perceptions of ad informativeness, entertainment, irritation and credibility. These constructs were used as predictors of advertising value in a structural equations model which was estimated with Partial Least Squares. Findings A substantial bias against sponsored results was found, with two-thirds of respondents skipping the ads when performing mobile search from their smartphones. However, 28.2% reported clicking on the most relevant result without regard to it being organic or sponsored, and an additional 5.6% reported clicking on an ad as their first strategy. In the structural model, all four hypothesized antecedents of advertising value were significant and some gender differences were detected. Practical implications With the increasing penetration of smartphones, and rapid growth of mobile search, these results are particularly relevant for local merchants, who can use mobile search ads to leverage their location and communicate with searching consumers at the precise moment when they are most receptive to timely and relevant advertising. Originality/value This study is the first to measure the extent of consumer bias against sponsored results in mobile search, and the first empirical estimation of the advertising value of mobile sponsored results.