I'm afraid I have to disagree with you here. I never believed that wearing a service signature in my profile could be considered a shilling. NO, We are not shilling their business. We are not advocating for them in the forum.
Shilling can be a wrong word to describe it but shilling, promoting have similar purpose. It is only different in quality of posts we are making. People who are in shilling services mostly newbies, spammers and their services only provide non sense posts to bump announcement threads. They will write something non sense like
1. No zero or low value, pointless or uninteresting posts or threads. [1][e]
1. Such posts as "SELL SELL SELL", "I agree", "+1", "Support", "Watching", "Interesting", "LOL", "SCAM", "LEGIT", "FAKE", other one word posts, posts consisting mostly of swearing, quote pyramids, useless introduction threads, threads about a topic already recently discussed in several other threads.
We as good posters will promote the company which hires us with higher quality posts. If we make posts in the company announcement thread, it is similar to shilling service but we do it when we want and if we have good discussion or contribution for the company to improve their games, products, services, customer supports or inform them about phishing sites.
The signature campaign never asks you to post and advocate for them. Let's say you are wearing the signature of Vbetftn. Do they ask you to post in their ANN? Do they ask you to say something about their casino in another thread? If not, This is not a shilling. Signature space can be considered ad space, and you are selling your ad space to that platform. Nothing else.
If you are a responsible participant, you will do it naturally and don't need them to ask you.