It's as predictable as falling leaves and as futile to stop. All that really happens is that victims become even more partisan. So I'm not going to tell you it's not helpful to your candidate (IT'S NOT HELPFUL) or tell you not to do it (DON'T DO IT!). I'm just going to repeat an evergreen story (a true one — the kind that makes for the best old stories) that shows how cheaters never prosper (just kidding — "The good guys always win" is a movie trope that doesn't apply in real life).
Our real-life story is from a police report from 2002. I'll let the reporting officer (R/O) tell the story.
R/O was driving down Northwest Highway at Skillman looking for an accident scene. R/O observed listed truck pulled over on the Skillman service road and suspect out of the truck pulling-up election signs. R/O thought this appeared odd so turned around and stopped listed vehicle at Skillman at Northwest Highway. Susp1 was the driver and Susp2 was the passenger. Both susps were asked for identification. R/O looked in the bed of the truck and there were approximately 10 political signs with the name "Pauline Dixon" on them. Susp1 was asked if Pauline Dixon was aware that he was pulling up her signs and Susp1 replied, "No". Susp1 was then asked if she was who he was running against and Susp1 stated, "Yes." Both Susps were released at the scene and the signs remained in the bed of the truck. Sgt Beck 3688 was notified.
Source: My Daily Dose via Archive.org.
In case you haven't put two-and-two together, "Susp1" is none other than Congressman Pete Sessions, who has represented Richardson in District 32 since that 2002 election in which he defeated the sign-less Pauline Dixon. That's right. Pete Sessions is a sign stealer. And today an honored member of the GOP leadership in Congress from a perennially safe GOP district in North Texas. Coincidence? You decide.
A copy of the police report in question is below: