The main thing though is that any church where the pastor is wearing a suit and tie is almost certainly a fundie one.
Not really. It largely depends on what part of the country you're in and the denominational tradition. Leaving aside the fact that you mean "conservative" when you say "fundie," rather than fundamentalist, it's not uncommon at all around here for a mainline minister to wear a suit and tie (or some kind of blazer with a tie). I have yet to walk into a Methodist service and see the pastor not wearing a suit or khaki's and a blazer (unless they're in a robe). Ditto for PCUSA (although I have less experience with them). Also I've been to one UCC service in my life and the pastor was wearing a dark suit, white shirt, and a red tie. Cooperative Baptist Fellowship pastors almost always dress up.
Actually in my experience pastors on the moderate end of the evangelical spectrum are far more likely to dress down than those in liberal churches.