Link to long but interesting article about this research. Doesn’t say much for the opsec of some using darknet markets and/or the dealers tech/social awareness – its easy enough to shut off geotagging on all phones and there are also still many standalone cameras very few of which contain GPS receivers.
Had a look at the maps showing where tagged pictures were found out of curiosity. The researchers have removed a number of decimal places from the GPS data to protect privacy; but for UK and NL there appears to be enough left to show which districts the dealers were from.
I noticed they were mostly all urban/inner city areas where there is likely to be an existing high prevalence of “street level” dealing and where dealers might think they are “untouchable” and take more risks – plus the profs only introduced about 1,5km position error into the co-ordinates which although it might mask the individual to some extent still feeds the local intelligence systems of cops and health authorities with usable location data..
https://medium.com/@roselisker/illuminating-the-dark-web-d088a9c80240#.ks648hwlg