Not liking the cost implies knowing the cost in advance. Does your website disclose that it's ad-supported, which data will be collected and how it will be used (which is required if your are based in the EU or offer service to EU-based customers) and whether you take responsibility for any ill effects from executing the ad code? Because otherwise it can be argued you are also "stealing" people's computing resources and personal data before they could make a conscious decision to "pay".

> steal

Theft implies that you are deprived of the item once it's stolen - this is not the case here, and the costs should be taken into account either way. You're comparing fractions of a cent from an ad view with $100. I'd feel much better about stealing the former than the latter even in case of actual, physical theft.

> they dont let you taste in advance

It doesn't have an impact on the "theft" scenario, but in case of a paid product I would still expect a refund if the bread is defective (moldy or fake) or was mis-sold with false advertising.