Proactiv to Justin Bieber -- Clean Up Your Act ... And Your Face

Justin Bieber will never get a sweet deal with Proactiv again if he keeps screwing up ... but even if Justin turns into a choir boy, he's gotta 86 those pimples.

It's hard to miss the zits on Bieber's face in the now famous mug ... pretty ironic, considering Bieber was a spokesperson for Proactiv in 2012.

Proactiv co-creator Dr. Kathy Fields tells us, she's seen the mugshot and it's clear Justin's stress is causing him to break out ... so they're gonna send him some Proactiv+ and X-Out to help get him back on track.

As for him getting a full-on spokesman deal again ... Fields says they look for people who are in "the right state to help others and right now Justin needs to get himself healthy."