Brettanomyces is considered a spoilage yeast since it can produce off-flavours in wines. There is more risk to wines from Brett in hotter vintages (stuck fermentations) and those with hail-affected grapes. There is no difference in Brett risk between wild or inoculated ferments.

Bibliography

Jamie Goode (Dr), The Science of Wine (University of California Press in association with Mitchell Beazley, 2nd edition, 2014), p150-157.

Oxford Companion to Wine 4th edition ed. Jancis Robinson MW and Julia Harding MW (Oxford University Press, 2015).