There are lots of things going on here:
1. Stereotype of women as gold diggers
2. Stereotype of women as manipulative
3. Benevolent sexism
The women = gold diggers stereotype is based on women using their sexuality to get stuff. In the DQ commercial, the girl is flirting with the boy, using her body language and smile to make him think she's interested in him. In exchange, he buys her an ice cream. Translation: women use their only asset (sex and appearance) and men use theirs (resources, esp money).
The women = manipulative stereotype comes into play mostly at the end when the girl arrogantly and with sass says, "It's like shootin' fish in a barrel." Even at age 9 (estimation) she knows what she can get by using her looks.
Now, let's talk about benevolent sexism: "Characterizing women as pure creatures who ought to be protected, supported, and adored and whose love is necessary to make a man complete. This idealization of women simultaneously implies that they are weak and best suited for conventional gender roles; being put on a pedestal is confining, yet the man who places a woman there is likely to interpret this as cherishing, rather than restricting, her (and many women may agree). Despite the greater social acceptability of benevolent sexism, our research suggests that it serves as a crucial complement to hostile sexism that helps to pacify women’s resistance to societal gender inequality."
The problem is that benevolent sexism is often unrecognized and when challenged, called "chivalry." It's seen as men just being gentlemen and women should be grateful for men being nice. Also, it isn't seen as sexism because women often benefit from it. Even if women benefit, it can still be sexist. Although on the outside benevolent sexism seems advantageous for women, it actually keep women from equality. Since benevolent sexism values women on the basis of their gender, men and women remain unequal. Some see this as "female privilege" but when looking at it that way, we ignore the actual problem: benevolent sexism. Roy says it well: "I think that some of the problems that men face now...are a direct result of the flaws a patriarchical system. It’s not that women have more power than men, it’s that patriarchy is an inherently flawed system that sets standards that are harmful to everyone. It’s a double edged sword."
This might be a bit outdated but it's a questionnaire that assesses your level of sexism, hostile and benevolent (via). Here for a breakdown of scores. And here for the PDF of the paper for you academic type ;)
Obviously DQ knew what they were doing. Why else did they put the little boy in a "donkey sweatshirt" (aka jackass)? Lots of money, time, and thought goes into developing these commercials to send a particular message, don't let them fool you :)