I find a lot of the southern white soul, and the whole idea of Blue Eyed Soul fascinating. Records by Ben Atkins, George Soul, Dan Penn, Eddie Hinton, Troy Seals, Johnny Daye and so on are very interesting from a sociological point of view. In all cases these singers made records which could be broadly termed blue-eyed soul, but are quite different to that strict definition. Their 45s were conceived wholly as soul records, hoping to appeal to exactly the same record buyers who were digging records recorded at the same studios by the likes of James Carr, Wilson Pickett, Sam & Dave etc.
As far as I understand it "Blue Eyed Soul" refers to pop records with a pronounced soul flavour or influence in both the singing and the musical setting which is distinct from an attempt to make 'real' soul like the artists mentioned above. Prime examples of this are acts like Dean Parrish, The Magnificent Men on Capitol, The Jaggerz on Gamble, and The Righteous Brothers, who came to define the genre. All of these acts definitely crossed over to African-American record buyers and the black club and concert scenes for a time in their career, but all moved on (or tried to move on) after one or two years of R&B scene acceptance, and tried to make more mainstream 'pop' records.
It's important to remember that 'soul' as a concept went some way beyond music in the mid-to-late 60s in America: it was a fashion, a feeling and a way of life for black and white metropolitan youth alike for a brief time. This has a modern parrallel in the way hip hop has been absorbed and assimilated into mainstream culture. But while hip hop has taken root in that culture, soul was kind of replaced and supplanted by other fashions like psychedelia throughout much of 'white' America. Think how hideously dated The Righteous Brothers must have sounded in 1967.
The Beach scene in the US was and is a fascinating case of the blurring of racial barriers. Most of the artists who created the orginal beach sounds were black, The Coasters, Showmen, Willie Tee and so on all making classic beach sounds which were picked up on by all-white audiences across the South East of the US. The beach fans themselves formed their own bands (Embers, Tyn Tynes, Oxford Nights, Tempests et al, sometimes with African-American vocalists, although this was by no means the norm) which took on all the characteristics of these records and aimed them straight back at the white teenagers who had been raised on the staple diet of black R&B.
More problematic to define are one-off single artists who made records which have been picked up by the rare soul scenes of Europe over the years. Lynne Randell, Joanie Sommers, Cajun Hart, Fifth Avenue Band and a cast of thousands of others would probably be amazed that their records are thought of as any kind of 'soul.'