They did say to me we have realised we cannot get the level of experience required at salaries quoted when I chased them up for a response. Feel like they were trying to get someone cheaper till then.Don't over think it - If it's not for you - politely decline and move on.
I was once offered a very good opportunity to build a business from the ground up with great support and huge supply of clients/leads etc - On the surface, fabulous but just one part of it I couldn't sell my soul for (long story won't post it all here) - after a lot of soul searching I declined. However, I sent a personal letter to the Managing Director of the business who "head hunted" me and a nice bottle of whisky as I knew he really wanted me to take it on. 8 years later, I'm on excellent terms with him still personally and professionally......
Don't burn your bridges, but be firm, and don't regret it
Yes I will be polite if I do decline. It is a pain when a recruiter is involved.