The James Webb Space Telescope (JWST) enables the identification of quiescent galaxies (QGs) out to early epochs, offering a transformative view of their evolution. However, photometric selection of quiescent galaxy candidates (QGCs) and the derivation of their key physical quantities, such as stellar masses (M*) and dust attenuation, remain highly sensitive to the assumed star-formation histories (SFHs), where dust-age degeneracies and modelling choices remain a major source of uncertainty. We aim to quantify how the inclusion of JWST/MIRI data and different SFH models impacts the selection and characterisation of QGCs. We test the robustness of the physical properties inferred from the spectral energy distribution (SED) fitting, such as M*, age, star formation rate (SFR), and dust attenuation (AV), and study how they impact the quiescence criteria of the galaxies across cosmic time. We perform SED fitting for ~13000 galaxies at z<=6 from the CEERS/MIRI fields with <=20 optical-mid infrared (MIR) broadband coverage. We implement three SFH prescriptions: a flexible delayed, non-parametric, and an extended regulator model. For each SFH, we compare results obtained with and without MIRI photometry and dust emission models. We evaluate the impact of these configurations on both the number of QGCs, selected based on rest UVJ colours, sSFR and main-sequence offset, and on their key physical properties such as M*, AV, and stellar ages. The number of selected QGCs varies significantly with the choice of SFH ranging from 70 to 100, out of a mass-complete sample of ~5000 galaxies, depending on the model. This number increases to 103-180 when MIRI data are included, driven by improved constraints on both dust attenuation and M*. We find a strong correlation between AV and M* of QGCs at z<=2.5, with massive galaxies (M*~10^11^M_{sun}_) being ~1.5-4 times more attenuated than low-mass galaxies (M*~10^9^M_{sun}_). Regardless of the SFH, ~13% of QGCs exhibit significant attenuation (AV>0.5) in support of recent JWST results on dust-rich QGs.