"One woman in particular was very upset and very rude. I think she complained to Bunnings," Ms Reus said.
Customer Olivia was surprised, too, see the vegan snarlers.
"We were a little shocked, considering it's probably one of the most male-dominated destinations in the country," Olivia told 3AW.
"We were like ... thank you, but no thank you."
At a November sizzle the group sold 1000 vegan snarlers to Bunnings shoppers, she said.
Cheltenham Cat Rescue was raising money to help pay vets' fees and also to kickstart a multi-lingual awareness campaign about desexing cats.
It raised $1300 at the controversial Mother's Day sizzle.
"I think we challenged people's ingrained habits and thought processes," Ms Reus said.
"We explained we were an animal rescue group so couldn't sell animals to eat and so people had to think about that."
Unfazed by the criticism, Ms Reus said: "At least we've got people talking about the issue."
Bunnings State Operations Manager, Tony Manzone, said for more than two decades, Bunnings has been supporting thousands of local community groups via the fundraising sausage sizzle.
"Since their inception the guidelines have been consistent. Meat sausages, onions and bread. This has not changed," Mr Manzone said.
"However, in recent years, and on a case-by-case basis, we also allow community groups to have a vegan fundraising sausage sizzle if that is their preference, which is supported by appropriate customer signage. In addition, our cafes provide vegetarian and other options for customers if required."