Pre-soul did he feel undeserving, though?

Good question. According to canon, pre-soul would be Dru (sire as mommy) and Harmony (Buffy substitute or easy lay?)

Harmony, though not crazy, was an air-head and eye candy. I can't see that he wanted to fix or help her in any way. In fact, he was very cruel to her. I think she was a target for his frustration re: Dru breaking up with him and later, a stand-in for Buffy.