DST samplers are capable of capturing downhole samples and recover them within the DST string this procedure has limitations and is considered to be “quick & dirty” sampling.
On the other hand, there are several situations where some operators are reluctant to run wireline bottomhole samplers. These include:
in HP / HT wells for safety to avoid a high pressure wireline rig up
in heavy oil wells because of problems in getting tools downhole through high viscosity fluids
in high H2S wells for safety reasons to avoid release of gas during wireline rig up
in deep water where moving off location with wire in the hole is considered as high risk
company policy which dictates wireline is to be avoided
where there is a risk that the well is not properly conditioned for sampling (absence of well testing equipment)