For devoted anime fans, there are few things more annoying than anime with too much fan service. While fan service can sometimes be kind of fun, when left in the wrong hands, it can wreck an otherwise good show. Most fan service is aimed at straight men, so its inclusion can potentially alienate or demean women and queer people. Even when that's not the case, excess fan service can make a good series appear ridiculously profane, which limits an otherwise brilliant show's potential reach. There are a ton of anime that didn't need fan service, as even without the added sexiness, they manage to tell wonderfully engrossing stories.
One of the biggest complaints some viewers have about Fairy Tail is the relentless fan service. Despite featuring interesting characters, a unique fantasy setting, and an engaging plot, many people give up on Fairy Tail after they have one too many encounters with Lucy's boobs. Often times, the show seems to use fan service in place of deep explanation. Instead of trying to develop romantic relationships between characters, the series opts for cheap gags involving heroes walking in on each other naked. Nudity should not be used to replace a storyline.
Yowamushi Pedal is a sports series about bicycle races. Fan service rarely appears, but when it does, it's pretty gross. While female characters are routinely shown in licentious situations, their role in the series is basically nonexistent. Miki and Aya are part of the Sohoku pit crew, and Miyahara is friends with a member of the opposing team. Their personalities are one-dimensional, and when they do get a moment in the spotlight, they usually just spend time thinking about the male characters. The way the series exploits these girls is a slap in the face to female viewers.
Sword Art Online is widely considered one of the most overrated anime of all time, and excess fan service is one of the main complaints levied at the show. Few people want to watch Kirito's adopive younger sister drooling all over him, and those who do should stick to Oreimo. The inbred, fan service driven plot line casts a creepy shadow over an otherwise genuinely exciting series, as it does little to develop the characters or advance the story.
Believe it or not, it's totally possible to have a campy, B-movie influenced zombie anime without resorting to cheap fan service, but High School of the Dead doesn't seem to have gotten this memo. Many potential fans are turned off by the show's decision to focus on a girl's panties while she's being eaten alive by zombies. Even those who stuck around probably take issue with her bullet-absorbing breasts.