1. Poor graphic design ... I say it loud, this could be first reason your website sucks. One of my clients told me that more than 50% of his visitors remained on his website after he redesigned his 90’s website. Awesome effect.
2. Too much flash on your website - Too much flash is not good for your SEO and also slow down alot your website for most of users. It also takes some badwidth use it wisely !
3. Bad navigation - Your website must be very friendly to all the users. Make sure all your visitors could see all the sections easy without spending hours ;
4. Audio & videos which auto start - this scared me one time when I visited a website ( they add a radio link which started without my click - rock music ).
5. Site intros - I’ve never agreed with this. Why should I wait 30 second or more to get in a website I want to see. You really want a intro?
6. Excessive advertisements - My uncle is new to Internet and what he hates the most are the aggressive pop ups, banners, flash ads which sometimes takes the whole page for few seconds.
7. Browser compatibility - Check twice your website in all major browsers and apply for 1024 x 768 & 1280 x 1024 before you publish it. Browsers understand in different ways html/css code.
8. Orphan pages ( back button is missing ) - make sure your visitor could easily leave a page but remain in your website.
9. Slow loading sites - Either you use too much flash or heavy backgrounds and images , too much youtube videos or audio files auto started your website will take forever to load.
10. Outdated information - If I’ll enter a website and I see in latest news "Britney is still virgin!" and I open the tv and I found out that she has 2 kids I’ll never visit that website again.
If you want to read the entire article visit my website