What a lot of people who travel do, myself included, is just stop at the first restaurant that is convenient. I might make a decision as to what kind of food I feel like having but the venue is kind of arbitrary. I am like most folks; I expect the operator of any establishment to protect my food from contamination. Most QSR’s are under some sort of quality system, self imposed of course because most health agencies do not require it. These places are inherently less likely to pass on contaminated foods because they have internal standards they must meet. This is the case for every restaurant; if the there is no continual assurance of safety on a daily then risks are higher. I frequent proprietary restaurants, those without a national "brand", but I also recognize risks are probably higher there.
So that is the basic idea. If the facility has a posted score from the regulatory agency, this is even better, because it means whatever internal programs exist they are validated.
You cannot tell the risk of contaminated food by observation of the eatery. It is absurd to suggest to consumers that they look around the dining area, closely watch the buss boy, or inspect the bathroom. That is not where contaminated foods come from. You, I and all consumers are basically putting our trust in the hands (literally) of folks we do not know. Doesn’t it make sense that the facility operator should be required to properly protect my food? If you can spend the time to learn the system ( they do not make it easy) take a look at the inspection records in Florida. What you will see are repeated cases of critical items out of compliance, and very spotty enforcement.
I do not become uninterested in food safety just because I am a consumer. In Florida, I ask to see the last inspection report (except when dining with my wife whom insists I do not do this). It is law that they show it to me. In Palm Beach  County, I look to see that the sign advising consumers that they may "request to see the latest report" is there. If they balk, I will report them.
The Florida Restaurant Association fought hard here to keep the restaurant inspection findings from posting, and have temporarily succeeded. They also are very much against any type of posted sanitation rating.
With the poor record of compliance in Florida (and most places) consumers need to have complete transparency to make a decision about where to eat
That is why my company provides a certification to restaurants that participate in my program, known as "Ten to Win" (see www.safefoods.tv). My perspective is consumers shouldn’t have to ask about compliance with the law, or guess about sanitation.