In part of the PTCAS application they ask about work experience. Out of curiosity, how favorably or unfavorably do admissions at most schools look at an applicant who maintained a part time job (15-20 hours) working through college?
I wouldn't think it would have much of an impact at all in relation to the main factors (GPA, GRE, Rec. Letters, and observation). It may speak to your ability to handle a heavy workload in doing both school and work. I'd say they look at that minimally in comparison to anything else.