The case is being heard in federal court because Swift and Mueller live in different states - Swift in Nashville, Tennessee, Mueller in Colorado - and damages at stake exceed $75,000.
Baldridge emphasized the age difference between Mueller, then 51, and Swift, then 23.
Mueller also testified that he felt "invisible" after concluding that Swift wasn't paying him professional respect during the one-minute meeting backstage.
Mueller talked about how he and his girlfriend at the time, Shannon Melcher, had gone to the meet-and-greet for work as KYGO employees despite not being huge fans of Swift's-as numerous other people at the pre-concert event were. After watching testimony all day in the courtroom, Chris Cain, a 31-year-old software developer, described the he-said-she-said allegations as "really off".
According to his suit, Mueller is accusing the singer of "intentional interference with contractual obligations" and "interference with prospective business relations" that led to lost wages.
The litigation was initiated by Mueller, who claims Swift fabricated the groping story and pressured station management to oust him from his job.
Mueller, wearing a smoke grey jacket and a white shirt, sat in court with his back to Swift and her mother, Andrea Swift.
Earlier Wednesday, court proceedings were delayed by a closed hearing that lasted almost two hours.
He co-hosted the Denver country music station KYGO's Ryno and Jackson show, as "Jackson".
But when Swift's attorney, J. Doug Baldridge, took over to cross-examine Mueller, Mueller was immediately put on the defensive.More news: Montreal Sets Up Temporary Shelters To Handle Influx Of Asylum Seekers
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Mr Mueller originally sued the singer in September 2015, calling her allegation of groping false and claiming she had cost him his $150,000 (£115k) -a-year job as a host at country station KYGO-FM after he was sacked over the allegations.
Swift countersued, claiming sexual assault, setting up the civil trial where she is expected to testify amid tightened courthouse security.
Swift's lawyer argued the entertainer also had no impact on Mueller's career stalling, saying the DJ had only sent packets containing his headshot, biography and audio samples to the top 20 radio markets following his dismissal from KYGO.
Mueller does not have a job in radio because he told 37 people about the accusations and because he hasn't applied for that many jobs, Baldridge said.
He was scheduled to resume testimony Wednesday after being grilled by Swift attorney Douglas Baldridge Tuesday about his claim that Swift falsely accused him of groping her before a 2013 concert.
Mueller took the stand Tuesday, saying a recording of him discussing the incident with his superiors at the radio station was accidentally destroyed when he spilled coffee on his laptop.
Mueller is suing for $3 million dollars. He hopes he can clear his name.
Taylor Swift is suing for just $1 from her sexual assault court case against DJ David Mueller.