While faked smallcaps look "wrong" generally (because they are too thin), they have a couple of advantages:
- It's easy to have them in different styles (italic, bold), while true smallcaps are often not available in some of them.
- They can look better when combined in with numbers (as in acronyms like P2P or B3LYP), although some true smallcaps may have matching numbers too.
But they also have another disadvantage:
- The markup is hideous, even more so if you want to be careful with the spaces (note that the spacing is the "fake" example is too tight), because these are not equivalent:
<span class="smallcap">TWO WORDS</span>
<span class="smallcap">TWO</span> <span class="smallcap">WORDS</span>
the space in the first case will be 75% of a normal space, in the second case it will be a normal space.