And yet you seriously need to "sell your sig space" for some tiny fractions of BTC?
Anyway - the whole point is not the "ad sigs" themselves but the "stupid pointless posts" that are being made in order to "earn that tiny amount of BTC". If you are not making stupid pointless posts then you should have nothing to be concerned about (and no-one is forcing you to ignore anyone).
I do it as a pass time and I am not obliged to answer anyone what I do and what I don't as being a part of a sig campaign isn't a crime. I don't earn my living being a part of a signature campaign as I have a full time job.
Being a part of bitcoins is in itself not a good thing as it isn't a recognized currency and considered ILLEGAL. I would rather argue about how to make bitcoins worth talking about and LEGAL rather than Sig campaign spammers. But unfortunately, I don't find anyone interested in making bitcoins a LEGAL currency or working on it as some people are happy about using it for gambling, money laundering, selling illegal goods and hence they don't want bitcoins to be regulated.
Errm, you do realize that there are only few countries who consider bitcoins as "illegal" right? And if you say that being a part of bitcoin is not good, then why the hell did you even involve yourself and joined this forum in the first place? Also, what do you mean when you say "legal"? Under some regulations and authority?