Since the dawn of HGTV, DIYers inspired by Pinterest, Instagram, and now TikTok have shiplapped, sponge-painted, and grouted their way to domestic bliss. On the flip (so to speak) side, social media is filled with DIY disasters and schadenfreude content, including mockery of overdone trends like barn doors and gray laminate flooring.  When it comes to home design and decor, of course, nearly everything is a matter of taste. For some, painting over the natural brick of an old fireplace is an aesthetic sin that cannot be forgiven — and yet sinners are everywhere.  But for Nate Austin , a professional chimney sweep in Butte, Montana, it’s a matter of safety. Austin has gone viral for roasting DIY fireplace paint jobs, warning that using regular latex paint can be a fire hazard.…