Online political advertising is often portrayed in a negative light, yet there is limited evidence about what exactly the public deems unacceptable about it. This paper provides new insights into public attitudes through an online survey where 1,881 respondents evaluated all political ads placed on Facebook during the 2019 UK General Election. We find that citizens do not inherently think political ads are problematic. Examining two possible regulatory responses, first, we find that compliance with existing regulatory protocols for non-political advertising is a strong predictor of political ad acceptability, suggesting a case for extending the existing regulatory regime to include political ads. We also find that people had particular concerns about the content and tone of unacceptable ads, highlighting the value of codes of conduct to promote good practice. Overall, this paper offers a nuanced account of attitudes towards online political advertising and identifies possible pathways for regulatory reform.