An always-present "help wanted" sign wouldn't turn me off. I've said on here before - there's not a "shortage" of machinists now, there's a high-powered sucking "vacuum" of machinists. Every manufacturing business needs more machinists right now, and every machinist worth their salt is already working in a job. It's a bad time to be looking for a machinist. It's a good time to BE a machinists...
The place with the always present "help wanted" sign could be a shady outfit that burns through people, or it could be a really well-run, great business that recognizes they need to be always on the lookout for skilled people, and snatch them up & make a place for them when the opportunity comes about. A quick stroll through the parking lot, to examine the age & condition of the employee's vehicles, is a pretty good litmus test to sort the place out...
The well-run shop with the "help-wanted" sign, is simply employing some "right place at the right time thinking." (I'm thinking about motionguru & his outfit here...) The well-run, turn-key automation shop that's always eager to add more talent - they're the "right place" looking for the "right person" and ready to pounce when the "right time" finally comes about. The "help wanted" sign just helps bring in the curious folk, in hopes they're the "right person."
The "Job Fair" would be a turn-off for me though. Especially having worked at a place that frequented job fairs, and had extremely high turnover. These places are like the "clinically insane" person, trying the same thing over & over, and expecting a different result "this time." Ain't gonna' happen. It's not the people they're bringing in - something else is broken. That something else simply amplifies the tendency to bring in the wrong people - who quickly leave. It's a downward spiral from there.