The 16-year-old disappeared on July 12, 2015, after allegedly meeting Rodney Wayne Williams, 65, for a paid sexual liaison arranged through the Oasis website.

Her body has never been found.

Williams has pleaded not guilty in the Brisbane Supreme Court to murdering Tiffany after allegedly picking her up from the Waterford Motor Inn, south of Brisbane, mid-morning.

Messages between the pair show Williams agreed to pay $500 for sex, but he says it never happened.

Witness Graham Dodd told the court on Wednesday he met Tiffany through Oasis but ceased communicating with her in the days before she disappeared because the teen suggested he pay for sex.

"Pretty much straight forward like that, 'will you give me some cash for sex' and I remember saying 'what are you talking about, we're a couple'," he said.

He said the teen said she was struggling and needed the money for rent.

Earlier, the court heard Tiffany got together with a man named Gregory Hill when he was 38 and she was 12.

Tiffany's mother, Leanne Dillon, said she was disgusted when she found her daughter giving Mr Hill a lap dance at their family home soon after.

Chloe Taylor said her younger sister began chroming and smoking cannabis on a regular basis about the same time.

Mr Hill says Tiffany pursued him when asked about his relationship with the then child.

He said the pair soon moved in together but denied he was the father of her unborn child and said they had never had sexual intercourse.

By the time she went missing, Tiffany and Mr Hill had been together for four years and lived in hotels, often paid for in cash by her sex work.

Mr Hill denied pimping Tiffany out or knowing she was selling sex.

However, 300 messages about meeting men and money were found on his phone.

The trial continues on Thursday.

Australian Associated Press