As far as fast-food restaurants go McDonalds have a reasonable reputation. I can think of worse. Places that sell doner kebabs or sushi need to be spot on to avoid salmonella and other forms of food poisoning. They'd be much riskier.
I have a distant relative who ate at a Chinese restaurant and explained to the waiter taking her order that she was allergic to peanuts. Perhaps she shouldn't have trusted him but she went into anaphylactic shock and never recovered. That's infinitely worse than McDonalds.
BTW I've only ever eaten at McDonalds twice in my life, and only when I couldn't find somewhere better, so I'm not a fan. I just don't think they're as bad as healthy eaters believe them to b e.
I would think KFC is worse. Yes....all fast food restaurants are unhealthy.. but some are trying to provide healthier options. McDonalds and Burger King are making attempts at healthier menu items but most people still go for the burgers, fries and shakes.
One of the worst, yes, but for me it's a sanitary thing. Years ago McD's used to be spotless. Now many are dirty & unkempt. Employees also handle food & money, & clear trash from tables at the same time. A big no-no in the past. But McD's is not the only one. I've seen workers at other chains carry garbage bags to filthy dumpsters then come inside & shovel fries, never stopping to wash their hands. And maintenance people stand on serving counters & customer tables w/ dirty shoes instead of using a ladder. Not the best places to eat for any reason.