One of the biggest problems I've seen lately are wheels that are too big. Several of my most recent builds have had wheels with excessive diameter, and they were stock builds. My current build, the recently tooled Fujimi Lotus Esprit is a perfect example. The Esprit should have 14" wheels, but the otherwise excellent kit wheels measure over 15.5" diameter. The kit tires have the correct profile for the wheel, but that makes the combination much too large in diameter for a stock ride height. The thing sits on its tippy toes, and no amount of lowering will stuff those big tires/wheels far enough up into the wheel well to give a proper ride height. The only solution was to fit low profile tires, but the final appearance is not stock.
I recently built the Aoshima/Airfix MGB, which has the same problem; 14" wheels that scale out to almost 16" diameter, and give an unavoidable tippy toe look. I lowered it some to improve the look, but a wheel/tire that is too big, looks too big. Both of these kits are not inexpensive, and modern-era tooled by fastidious Japanese kit makers.