Since the content-injection work in BP 1.7 (primarily by @jjj I think), any complete, properly written WordPress theme will display BuddyPress content using vanilla theme elements provided as part of the BuddyPress plugin.

However, if you want to customize those elements, or have them look more like your theme, your WordPress theme will either need to include css for the BuddyPress-provided markup, or include BuddyPress-specific template files and css.

BuddyPress isn't all or nothing, though. If, mostly, the vanilla BP-included theme works fine with your WP theme, maybe you only need to provide one or two template pieces to scratch some itch that bugs you. Read more about the template hierarchy: http://codex.buddypress.org/themes/theme-compatibility-1-7/template-hierarchy/

So any well-written theme will be BuddyPress compatible. But some go the extra mile and specifically include BuddyPress template pieces or css for more customization.