There's only 1 thing that's damaging Liverpool's reputation.
No League Title for 18 years. That's it. In fact, they've only broken into the top 2 once in the last 17 years.
Prior to 1992 Liverpool were widely considered to be the biggest club in the country, and Man United had a similar reputation to the one Liverpool have now.
Why? Man United hadn't won the league since 1967.
In 92 though, Man United finished 2nd, then won the title in 93 and went from strength to strength. Liverpool on the other hand started to fade, and got left behind.
Quite why they're incapable of mounting a serious title challenge these days I'm not really sure. Every year a few people tout it as being Liverpool's year, and often they start well, but always fade at the end. It's a bit baffling really. They have the resources to challenge, but for some reason they can't quite get it together.
Can't compare them the Spurs really. In the general scheme of things Spurs are just chumps in comparison to Liverpool.