wheel - 10:51 pm on Mar 18, 2010 (gmt 0)
I've done occassional SEO in my industry for direct competitors, in the past. But they knew upfront what was going down, and they trusted me to do the job right.
The advantage - if they're straight up - is that they should know the industry cold. And typically there's enough business for everyone.
I've also been selling website widgets to my direct competitors for years. I quit doing that in February this year - and my competitors are struggling to find a suitable replacement. They're not happy.
My take is this.
1)If they were upfront, there may be some advantages i.e. industry knowledge.
2) If they weren't upfront, drop everything and run.
3) why are they in your industry and doing seo? They need to pick one. in my case, I eventually decided that I need to 'be' the competitor and I've dropped everything to focus on my own SEO for my business, with the intention of dominating my niche. Be careful you're not funding a monster (not that that's what happened in my case, but the similarities are there).