@WellErrr
obviously there are lots of brands we won't work with and formats we turn down...
Oooh who? 
Well, the current list, which is always a work in progress, as agreed in consultation with Mumsnetters or just because we at HQ don't think the advertiser fits with Mumsnet's purpose - i.e. to make parents' lives easier- is as follows:
Nestle and any brands in which they hold majority ownership.
Formula milk - not because we are anti formula feeding per se but because the whole concept of follow-on milk was invented to avoid govn. ban on advertising formula milk
Exclusively bottle feeding products
Weaning foods for under 6 months
Payday loans - eg wonga
Dodgy weight loss products - eg diet pills - and pharmaceuticals
Spammy things - like PPI or accident or injury lawyers
Cosmetic surgery
Gender specific advertising - we recently vetoed a campaign to market a dinosaur toy just at mums of boys.
Sea world
Thomas Cook
We would be wary of advertising featuring pre-pubescent looking models - eg American Apparel or Beach Body ready type advertising.
We are also very selective about Sex Toys (IYSWIM) - if the site objectifies women we would reject
The Baby Show - (organisers also promote an Arms show)