[3] The protagonist, Alexandra or simply "Alex" (performed by Claudia Claire[2]), is smart and successful, but apparently prudish:[3] a 'good girl' who often thinks about sex, but usually doesn't act upon it.

[3][2] When the doorbell rings, Alex exits the shower with just a towel wrapped around her body and opens the door to find an unexpectedly attractive pizza delivery man (played by Lucas Foz).

[1] She set up her company Lust Films with the help of an investor and friend, who invested 30,000 euros in producing The Good Girl as a pilot to spread their business idea.

[18] The Good Girl set the tone for Erika Lust's filmmaking style,[19] and launched her career as 'one of the most celebrated feminist pornographers in the world'.

[3][22][6] Some subversions noted by commentators include challenging the traditional dichotomy between the "prude" (Alex) and the "courtesan" (Julie) by presenting a complex female protagonist who 'overcomes her hang-ups so she can enjoy––on her own terms—her body and sexuality';[3] respecting the female body by showing complete bodies and focusing of facial expressions;[3] Paulo not being a confident man who takes the initiative, but puzzled and astonished, just trying to do his job while patiently and gently waiting for Alex to make her first moves at several occasions;[23] and Alex being curious, joyful and playful,[3] having 'real breasts', not wearing high heels,[6] not being aroused by Julie telling about her sexual experiences,[6] and not 'swallow[ing] the male's penis like a human vacuum cleaner.

'[6] Anne Sabo (2012) described the decisive scene in which Alex and Paulo stare at each other as 'comical, embarrassing, and heartbreaking all at the same time, but it has to be now or never; she lets the towel fall, peeking up at him.

[22][6] Anastasia (2006) stated: 'Outside of this one teeny weeny element [the facial], for me, the remaining 99.9% is appealing, humorous, sharp, erotic, sensual, playful and interesting.

'[24] Lust (2007) retorted, mocking 'the Church of the Pure Feminist Porn Producers... declaring that certain sexual practices that me and other women across the world happen to like, are a sin.

[2] On the other hand, Heck (2021) was generally positive about the film, arguing that Alex's vulnerability was 'carefully contextualized' within a wider narrative of having agency, gaining courage and taking initiative.

[27] '[T]hose who regard facials as unavoidably misogynistic (...) will be unimpressed', but in that case 'it has little to do with pornography but rests upon an independent claim that a certain sexual act is always unethical, even when it is enthusiastically consensual and wanted.

'[26] Nevertheless, Heck pointed out a further sequencing error similar to how 'contrived' facial scenes in mainstream porn are, which undermined The Good Girl's 'subversive potential': 'The sex overall is convincingly realistic: the kind of thing that people like Alex and Paulo might actually do.