Scheer was one of the original nine cast members of Mad TV when the series debuted in 1995. She came to the show with a background in sketch comedy from her Groundling days. During her tenure, Scheer developed characters like chain smoker Mrs. Jewel Barone, Cabana Chat host Dixie Wetsworth, Connie Linder, Debbie Dander, Lily Don, and Mrs. Vigor (Killer Grandma).

Scheer also performed impressions of celebrities and public figures during her tenure on Mad TV, some of which included U.S. Attorney General Janet Reno, Demi Moore, Susan Sarandon, Kathy Griffin, Mary Tyler Moore, Melissa Joan Hart, Ashley Olsen, Candice Bergen, Fran Drescher, Shirley MacLaine, Emma Thompson, Frances Bavier, Irene Vernon, Ashley Judd and Barbara Feldon. Other impersonations include Barbra Streisand in the Mad TV spoof video “Terms Of Imprisonment”, where she portrays Streisand as an egomaniac who abuses her co-star, Whitney Houston and Gillian Anderson’s Dana Scully in the “XXX Files” sketch. During the second season, Scheer became visibly pregnant and continued to perform on the show. After giving birth, Scheer finished the second and third seasons before leaving in 1998.