Yeah, thats the other thing: When you use a "shiny" spray, it attracts dust and dirt, making the engine bay dirtier, quicker. I used to detail cars, and my boss tire shined everything. Even the A/C vents and pedals (dangerous). I had a firebird formula and what I did was use the degreaser and pressure washer to clean the engine, and no dressing. It stayed clean till the day I sold it, and I drove it EVERY day.
I did get a little nuts with the tire dressing elsewhere, though. I used it on the wheel wells to make them look new, and a little known trick is to use it on painted rims, as in not polished or chromed. It gives them a uniform look and the next time you wash the brake dust comes right off. I had the stock "snowflake" rims, which were next to impossible to clean. The tire dressing idea kept them spotless. It also hides imperfections in clear coated rims.
My formula was so frickin' clean, I used to buff it every other week and wash it twice a week. I miss that slow ass car......