Do volume pedals ruin tone ? Some tone-conscious players refuse to use them.

I use a "Goodrich",the pedal steel players choice,and I haven't noticed any tone loss.I use a relatively short cable and its 1st in my chain.

I use the volume pedal on my DigiTech XP-100 Whammy Wah pedal and it doesn't, too my ears,
ruin the tone.

I have a stock mono Ernie Ball.
I never noticed any tone suck when I used to use mine, although I didn't
use it in the conventional application.
I would put it in the chain with other pedals and such, only I would just use it between songs to shut the rig off like a standby. Then when it was time to play another selection I would just floor it. Other than that I would use it for the swell thing. That may take a little time to master for the average Joe. For this the most essential thing would be a good tube amp. Anybody else have anything?

Don't know if it's of any help but here it goes anyway...

I've played with a Morley Wah/Dist/Vol, a Boss FV-50H, and an Ibanez VL-10. I've owned all of these, the only one not in my possession right now is the Boss.

I've found that none of them ruined my tone, but I've also found out that not all volume pedals are created equally... I've found hard to use the Morley volume for anything else than a full on or stanby situation.(wich is sometimes all you need one for)
The Boss and the Ibanez are way better for swell and violon type of effects, mostly due to their pots. The Boss and Ibanez both hane a minimum volume so you can set them to have a minimum or your choice, so you can alternate between full on and whatever you set it for. Both Boss and Ibanez are stereo pedals 2ins 2 outs and an added tuner out.

The Ibanez pedal is the only of that batch to have an added feature for panning, wich you can use in many ways, such as panning between 2amps for stereo setups, wich also let you control the "mix" of both amps... or you can also use it as an aby pedal... but still using it for panning, if you want to switch to volume mode, you have to bend down and switch it back on volume mode.

Lot's of infos here, but if you're considering buying a volume pedal, please do try ity and compare it prior to buying as they're not all great for swell... than again it all depends on what you need and plan to do with it.

Hope this somehow helps

If you're looking for a "swell" effect, definately try the Goodrich or Ernie Ball pedals. Both are available in either mono or stereo and are completely passive.And,if anything wears out replacement parts are available and easy to install.The only downside is that they're large and a little expensive.