Please imagine I put these 3 links in my signature. will google consider/count these links? is it bad for seo? imagine I put 1. http://mysite.com/ 2. http://mysite.com/blog 3. http://mysite.com/page1.php in my signature. All 3 links point to the same domain but different pages. will google consider these links bad links or link farm?
No single link will ever flag you for link farming. Link farming is about a pattern. Particularly a pattern of inbound links that don't seem to relate to the destination domain.
I will say this though, the BEST way to look at forum links is a way to drive traffic, and get people from your niche interested in your website. We get some traffic from DP, but the best forum we are in is a small business forum where we offer advice to small businesses. On that our links are related to small business, so it attracts a lot of attention.
Google would not count them as bad link profile. However, the links pointing to same domain from one website/domain would not help you much either. If you have to rely on forum signature link then I would recommend to participate with more relative forums. The more dividend, the more power to overall your link profile.
I don't think this will help you much, but it certainly won't hurt you. Google is virtually never going to punish you for doing something reasonable – the only time you really need to worry is if you're going out of your way to try to game the system.
No it is not bad. you actually need to promote your deeper page link to get good position in search engines.