Nothing is crappier than going to smaller restaurant (and some times even big ones) and drinking a skunked beer. Half the time you could have the manager test it and they wouldn’t know the difference between a fresh beer and an off tasting one.
Tap beer is great. It is profitable, and an easy sell. If you are going to do it, take the time to do it right and put in place the things you need to succeed. This includes staff training, cleaning schedules, glass/mug cooling space… Get your equipment set. Keg fridge, chilled lines, nice taps. Servers need to be knowledgeable about beer. I once ordered a Leinenkugel’s in Iowa and they insisted it was an import instead of a domestic beer. Even a small variation in CO2 pressure can make your beers all come out half foam. Head is great and all, but not that much.
Nothing says poor attention to detail than that first sip of beer that tastes bad. It sets a tone for the entire meal, and the customers that are unhappy (regular beer drinkers) won’t be back, and most won’t even say anything. They are the ones who order a bottled beer after their first tap beer.