I'll fill one out if it is there and there is a pen handy. For much the same reason as Christine Leigh Langtree, except I used to work in first line customer service as opposed to marketing.A tip is a direct gesture of thanks to your server but hopefully the comment card makes it up the hierarchy also and gets recognition of the person at those levels also.Equally, if I've not been happy with my visit I'll say so but only when it is not related to the server, who I normally just have a conversation with person to person on the rare occasions this is so. Criticise in private, praise in public etc.