Do speaker cables have to rest on floor?

You don't need to have your speaker cables in a straight line. Where did you read that? Just keep them more than 6" off the floor and all will be fine. I use a 3M tape on wall hook for one side and a wire metal piece (intended for something else) for the other side to suspend the cables. 

It's no more clutter than the cables themselves and makes for easy cleaning of the carpets around them. It also helps to have not lots more cable than you need and therefore, not much more to suspend. 

All the best,
Nonoise

Ignore the audio police.

Let those cables lay on the ground and enjoy listening to music.

Yup off the floor makes it a lot easier to clean under. Remember the magic happen on the outside of the wire not the inside. The fields expands and contract. Do they sound better laying on the ground with static discharge and dust bunnies or off the ground with a narrow insulated lifter and vibration control? Cable routing is an art, it's just as important as the cable construct it's self..

BUT if your a hook, drop and let er flop, kind of person, I'd stick with XLR and watch the routing just to STAY out of trouble, instead of getting out of trouble..

Regards

Best is to install speaker cables in galvanized conduit secured at either end. This way they run absolutely straight in a slope from the amp up to the speakers. Nice straight line, no unsightly cable risers. If worried about stress have a metal shop arc weld them at both ends. 

Not down hill? they go faster that way, uphill they slow down a bit..

Just saying, it's on the "water flows down hill principal, but not so well up hill". 

Regards

Fifteen years ago, I was young to the audiophile hi-end world. I had just started writing in a local magazine as reviewer, and had already reviewed some expensive gear. So I met this guy in a friend's shop and we met regularly at the same shop, discussing and listening various systems. 

He invites me at his home to listen to his system, he described a really expensive one. 

And so there it is... Zarathustra turntable, big Kronzillas power amps, Acapella speakers, Nordost reference cables... He puts the music on and it is really best I have everh heard in my life. A stage made of cement and the female voice that was singing was whispering in my ears like an angel... 

Then I notice that the speaker cables were put on a small "stand", wooden with spikes, not touching the ground. I knew this was not at all cheap, costing more than 300 euros... Skeptical I am telling to him: Everything is amazing but I think this device there is totally nonsense... A total cheat...

He replies: Why not make some tests. Let's remove them... He removes them and I have my jaw hanging.... WTF I tell him, the concrete stage is gone, it's very  good too now but THAT stage is gone... And and the voice .... not the same.... Damn! 

I tell him (still not believing), I want to blind test it!!! Well, we did and the result was the same....

@millercarbon 

uphill both ways…. Monty Python

Ayre makes some nice Myrtlewood blocks, beeswax candles in a pinch, dixi cups, etc.

I am sure that you have some spare cd cases which make great cable risers.  Just open them up, rotate them 90 degrees and you have a nice, sturdy, inexpensive 6" cable riser.

No cable risers let them rest on the floor for more static then pretend they sound great.Get Shunyata cable risersASAP!!

I bought risers and they make zero difference. YMMV.

@jl1ny but they do look cool and make cleaning easy at least my cleaning lady said so.

I am not a Robot I am a Dalek.

Very sharp!!